Errr, I think Utorrent makes some trick... it sort of installs itself somewhere after first run. I will have to check these days.
I could offer you the following solution:
1. Either distribute all languages in a single package, considering that they wont' take so much space.
2. Another solution I've seen- one installer with all languages and one with English only.
Anyway, in my opinion a zipped (7zip, whatever) package shall always be available for download. I is a pain to installsomething, then copy it somewhere and the uninstall it.
As a matter of fact, recently I tried to run my app in Windows 7 and it gave some error due to access rights, but this happened even when running it from the My Documents folder. Reading you explanation about MacOs, I think that the idea of two distros (one full and one English only) should be less problematic, unless you have a Mac to try.