I haven't looked to see - but there is a 4th Harvard style "Open University Harvard Style" that is different yet again.

I have fiddled around with the Chicago author-date style so that it gives the sort of in-text citation you are looking for. I played with the Harvard style for a bit but couldn't get it to produce the same result. Anyway, I'm pasting the Chicago below in case it is of use to you.

<?xml version="1.0" encoding="UTF-8"?>
<style xmlns="http://purl.org/net/xbiblio/csl" xml:lang="en" class="in-text" >
<info>
<title>Chicago Manual of Style (Author-Date format with colon in-text)</title>
<id>http://www.zotero.org/styles/chicago-author-date</id>
<link href="http://www.zotero.org/styles/chicago-author-date"/>
<author>
<name>Julian Onions</name>
<email>julian.onions@gmail.com</email>
</author>
<category term="author-date"/>
<category term="generic-base"/>
<updated>2008-02-12T23:58:00-05:00</updated>
<summary>The author-date variant of the Chicago style, hacked by Matthew T. Bradley to use a colon as separator in in-text citations rather than a comma</summary>
<link href="http://www.chicagomanualofstyle.org/tools_citationguide.html" rel="documentation"/>
</info>
<macro name="editor">
<names variable="editor">
<label form="short" text-case="capitalize-first" suffix=". "/>
<name and="text" delimiter=", "/>
</names>
</macro>
<macro name="series-editor">
<names variable="original-author">
<label form="short" text-case="capitalize-first" suffix=". "/>
<name and="text" delimiter=", "/>
</names>
</macro>
<macro name="anon">
<text term="anonymous" form="short" text-case="capitalize-first"/>
</macro>
<macro name="author">
<names variable="author">
<name and="text" name-as-sort-order="first" sort-separator=", " delimiter=", "
delimiter-precedes-last="always"/>
<label form="short" prefix=", " suffix="." text-case="lowercase"/>
<substitute>
<names variable="editor"/>
<names variable="translator"/>
<text macro="anon"/>
</substitute>
</names>
</macro>
<macro name="author-short">
<names variable="author">
<name form="short" and="text" delimiter=", "/>
<substitute>
<names variable="editor"/>
<names variable="translator"/>
<text macro="anon"/>
</substitute>
</names>
</macro>
<macro name="access">
<group>
<text variable="URL"/>
<group prefix=" (" suffix=")">
<text term="accessed" text-case="capitalize-first" suffix=" "/>
<date variable="accessed">
<date-part name="month" suffix=" "/>
<date-part name="day" suffix=", "/>
<date-part name="year"/>
</date>
</group>
</group>
</macro>
<macro name="title">
<choose>
<if type="thesis">
<text variable="title"/>
</if>
<else-if type="book">
<text variable="title" font-style="italic"/>
</else-if>
<else>
<text variable="title"/>
</else>
</choose>
</macro>
<macro name="edition">
<choose>
<if is-numeric="edition">
<group delimiter=" ">
<number variable="edition" form="ordinal"/>
<text term="edition" form="short" suffix="."/>
</group>
</if>
<else>
<text variable="edition" suffix="."/>
</else>
</choose>
</macro>
<macro name="volumes">
<group delimiter=" ">
<number variable="number-of-volumes" form="numeric"/>
<text term="volume" form="short" suffix="." plural="true"/>
</group>
</macro>
<macro name="publisher">
<group delimiter=": " >
<text variable="publisher-place"/>
<text variable="publisher"/>
</group>
</macro>
<macro name="year-date">
<date variable="issued">
<date-part name="year"/>
</date>
</macro>
<macro name="day-month">
<date variable="issued">
<date-part name="month"/>
<date-part name="day" prefix=" "/>
</date>
</macro>
<citation>
<option name="et-al-min" value="4"/>
<option name="et-al-use-first" value="1"/>
<option name="et-al-subsequent-min" value="6"/>
<option name="et-al-subsequent-use-first" value="1"/>
<option name="disambiguate-add-year-suffix" value="true"/>
<option name="disambiguate-add-names" value="true"/>
<option name="disambiguate-add-givenname" value="true"/>
<option name="collapse" value="year"/>
<layout prefix="(" suffix=")" delimiter="; ">
<group delimiter=":">
<group delimiter=" ">
<text macro="author-short"/>
<text macro="year-date"/>
</group>
<text variable="locator"/>
</group>
</layout>
</citation>
<bibliography>
<option name="hanging-indent" value="true"/>
<option name="et-al-min" value="6"/>
<option name="et-al-use-first" value="1"/>
<sort>
<key macro="author"/>
<key variable="title"/>
</sort>
<layout suffix=".">
<group delimiter=" ">
<text macro="author" suffix="."/>
<text macro="year-date" suffix="."/>
</group>
<choose>
<if type="article-newspaper article-magazine" match="any">
<group delimiter=" ">
<text macro="title" prefix=" " suffix="."/>
</group>
<group prefix=" " delimiter=", ">
<text variable="container-title" font-style="italic"/>
<text macro="day-month"/>
<text variable="edition"/>
</group>
</if>
<else-if type="thesis">
<text macro="title" prefix=" " suffix="."/>
<group prefix=" " delimiter=", ">
<text variable="edition" suffix=" ed."/>
<text macro="editor" suffix="."/>
<text variable="genre"/>
<text macro="publisher"/>
</group>
</else-if>
<else-if type="book">
<group delimiter=" ">
<text macro="title" prefix=" " suffix="."/>
<text macro="edition"/>
<text macro="volumes"/>
<text macro="editor" suffix="."/>
<text macro="publisher"/>
</group>
</else-if>
<else-if type="chapter">
<group delimiter=" ">
<text macro="title" prefix=" " suffix="."/>
<group class="container" delimiter=", ">
<group delimiter=" ">
<text term="in" text-case="capitalize-first"/>
<text variable="container-title" font-style="italic"/>
</group>
<text macro="editor" prefix=" "/>
<group delimiter=" ">
<text variable="volume" prefix="Vol. " suffix=" of"/>
<text variable="collection-title" font-style="italic"/>
<text macro="series-editor"/>
</group>
<text variable="page"/>
<text macro="publisher" prefix=" "/>
</group>
</group>
</else-if>
<else>
<group suffix="." >
<text macro="title" prefix=" " />
<text macro="editor" prefix=" "/>
</group>
<group class="container" prefix=" " suffix="." delimiter=" ">
<text variable="container-title" font-style="italic"/>
<group delimiter=":">
<group delimiter=", ">
<text variable="volume" />
<text variable="issue" prefix="no. "/>
</group>
<text variable="page"/>
</group>
</group>
</else>
</choose>
<text prefix=" " macro="access" suffix="."/>
</layout>
</bibliography>
</style>

Article: Newspaper - anonymous (no name
of reporter/author)


Title of article. Date. Title of newspaper: page reference,
Month and day.

Harvard	New drug appears to sharply cut the risk of death from heart failure. 1993. The Washington post: A12. July 30.
Notes	In text referencing: ("New drug", 1993: A12) The Title of the newspaper in italics. Give the correct title of newspaper, e.g. The Argus (not only Argus). The title of newspaper is followed by a colon, unless the volume or issue number is known. Treat this resource like a magazine or journal. The day of the month follows the page reference.

Book: Corporate author


Author. Date. Title: subtitle. Place: Publisher.

Harvard	a) Sanlam. 1998. Annual report: 1998. Bellville: Sanlam. b) Employee Benefit Research Institute. 1992, February. Source of health insurance and characteristics of the uninsured (Issue Brief No. 123). Washington, DC:Oxford University Press.
Notes	When an organisation "writes" a book it is known as the corporate author. Example a) Sanlam is the name of an organisation. Sanlam is also the publisher. The date of the annual report is also part of the title.

Book: Single author

Author. Date. Title: subtitle. Place: Publisher.

Harvard	Chase, Jennifer A. 1979. Advertising: the hits and myths. New York: Doubleday.
Notes	The subtitle: a colon after the title, space and then the subtitle. The subtitle starts with a lower case letter (...: the hits..)

Book: Edition other than the first


Authors. Date. Title: subtitle. Edition. Place: Publisher.

Harvard	a) Brunner, H. 1972. Hieroglyphic writing: the Egyptian legacy. 3rd rev. ed. Oxford: Oxford University Press. b) Mitchell, T. R, & Larson, J. R. 1987. People in organizations: an introduction to organizational behavior. 3rd ed. New York: McGraw-Hill.
Notes	Subtitle: separated from the title with a colon. The first word of the subtitle starts with a lower case letter. The title ends with a full stop before the edition (3rd rev. ed.) statement.

Book: Editors (or compilers)


Authors. Date. Title: subtitle. Place: Publisher.

Harvard	Gardner, B.P. & Smith, G. (eds). 1984. Child psychology: an introductory guide for parents and teachers. Harmondsworth: Penguin.
Notes	Always place an ampersand (&) before the last name. The editors (eds). must follow the names. Lower case e in 'eds'. The first word of the subtitle starts with a lower case letter (an...).

Book: Review - Author of review indicated)


Author of the review. Date. Title of the book being reviewed,
Author of book. Reviewed in: Title of journal review is
published in, Issue:Page reference, Date of issue.

Harvard	Reagan, M. 1997. The beach, by Alex Garland. Reviewed in: Village voice, 42:56, March 11.
Notes	Alex Garland has written the book with the title The beach. M Reagan wrote a review of the book in the journal with the title Village voice. Both the title of the book and the title of the journal are in italics.

Conference proceedings


Author. Date. Title of paper. Title of published document,
Place and date of conference, page reference(s), Place (of
publication): Publisher.

Harvard	Truter, Mavis. 1994. The role of the court interpreter in the new South Africa. Proceedings of the 1994 Conference of the South African Institute of Translators, Bloemfontein, 18-23 June 1994, 46-59. Johannesburg: The Institute.
Notes	Published conference proceedings. Cite only the paper read by Truter. Title of the paper: "The role of the court...". Title of the published volume: "Proceedings..".

Correspondence


Author of the letter. Date. Description of the type of correspondence,
Date of correspondence. [Note of location of the original
document]

Harvard	Theron, C. 1997. Letter to the Town Clerk of Stellenbosch, 5 May. [Original copy in records of the Town Council of Stellenbosch.]
Notes

Course notes


Author. Date. Title: sub-title. Place: Name of Institution.
[Indicate that these are course notes]

Harvard	Roux, B. 2003. Reasons for Absenteeism. Cape Town: Cape Technikon. [Course notes].
Notes

Dictionary


Title: subtitle. Edition. Date. Place: Publisher.

Harvard	a) Merriam-Webster's collegiate dictionary. 10th ed. 1993. Springfield, MA.: Merriam-Webster. b) Shorter Oxford dictionary. 9th ed. 1993. Oxford: Oxford University Press.
Notes	The position of the date - it follows the title and the edition. Merriam-Webster is a publisher. MA - the state of .... in the United States of America. It is customary to follow place names in the USA with the abbreviation for the state. Click here for a list of abbreviations for the states.

Encyclopaedia - Author indicated


Author. Date. Title article. Title of encyclopaedia,
volume of encyclopaedia, page reference.

Harvard	Lessing, B.P. 1985. Nuclear energy. McGraw-Hill encyclopedia of science and technology, 12:127-129.
Notes	NB. The title of the encyclopedia is in italics, NOT the title of the article.

Is it possible to provide a collection of "recipes" to make some of this easier?

I want to bracket the year of books and can't figure out how to make this change from one of the existing Harvard styles.

I also want to have a name like Luke Boys become Boys, L. in output. How should the .csl file be set up and can I just enter the full names as relevant?