i unlocked my treo 650 from cingular-only version to the unlocked gsm inserting the 9digit unlock code.

but my phone is ever in english,i want just to change the language.
however,my software version is "xx-cnb",so i cannot choose the language after an hard reset.
I need to upgrade the treo with latest unlocked firmware to get the language support?
i can do that?the cingular version allow to do this?

please,answer to my question only if you have experience,i don't want to do a mess with my new phone

thanks anticipately