I tried the locale-gen method above-thanks! I read some posts about optifying the locale-archive that seemd to imply it may cause some problems, so I shyed away from that.

Edit: just rebooted and lost all the proper text from all system buttons and widgets. In the Settings menu under regional settings, my location has changed and anytime I select and save my proper location, the device reboots and doesn't keep my location (shows Algeria, the first item in the list). No languages are shown at all.

Fixed it by following this post (which basically just rebuilt my whole local-archive).
http://talk.maemo.org/showthread.php?t=52443&page=4

Perhaps I was missing something from my locale.gen file that was required? I am using both en_US and en_CA, so I had this in my file:

en_US.UTF-8 UTF-8
en_CA.UTF-8 UTF-8

However, on reboot all menus and system widgets have missing text, as described in this thread: http://talk.maemo.org/showthread.php?t=52443 (which is the thread that made me think purging locales wasn't as straight-forward as it was on the n810 )

Edit2:

Added en_US ISO-8859-1 and en_CA ISO-8859-1 to my locale.gen file and tried locale-gen again. This time it worked great (menus and widgets fine), and my locale-archive is only 1.5mb instead of 22mb.

Thanks!