Portable Zotero.
In reading the documentation I did not see one obvious way to make Zotero portable. I took the base folder for the reference database and such and copied them to my portable hardrive. Then I point Zotero to that directory instead of its default. Then I just install Zotero on several computers. So far this has worked well with one install of Zotero on my home intel iMac and another installed on my work PC.
Your approach works too--just make sure that you use the same version of zotero on the different machines.