Hopefully the bugs that currently prevent switching locales (#5788 and #5755) will be fixed for alpha 2; otherwise all those catalogs will not get any exposure. hint hint ;)
You still can select the Locale at first boot from ReadOnlyBootPrompt if you boot from a CD (or launch it by hand, but who would do that ?) As for the bug, I'm now back to school and have little free time, but I'll try to have a look.
-- Adrien Destugues / PulkoMandy pulkomandy.ath.cx