Android does not allow you to change the language standard of your application; this is done at the system-wide level.
I would suggest that it makes more sense than installing a language in several separate applications.
Edit, 2010-03-09:
Apparently, I am mistaken that this is not possible for every application.
Here's a question showing that you can change the locale - apparently for activity. In this case, you need to take care of the screen rotation and other configuration changes manually, since otherwise the Activity will restart and return to the original Configuration when something changes.
Changing the locale inside the application itself
Android - Force locale copied with orientation changes
Christopher Orr Jan 16 '10 at 20:08 2010-01-16 20:08
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