After much research, it appears if your tablet doesn't have the language you want on it, you can't just add it.
By languages, I mean from within the settings menu and switching the entire tablet into that language and all the menu's and labels appear in your selected language, not just displaying it or being able to input it.
So the solution is (for other's who are wondering the samething):
1. root it
2. install Clockworkmod (cwm) from the Market
3. back up your original rom
4. install a stock rom supporting your specific model (3g, 4g, wifi only etc)
It's quite simple, i've never done it before and I did it in under an hour (including downloading times)
I won't go over the steps, google is your friend... do at your own risk!
Hope this info helps somebody out, I wasn't able to find many details on this topic