My grandmother doesn't understand english and I really like to add the Magyar language to her cell phone.
The way I see it I should install some software or do firmware update... the only problem that even if there is information in the nokia hungarian site - I would not be able to understand it.
Thanks Asaf
Your first and official option is to go into a Nokia Care point, assuming there is one nearby, and just ask them is it possible to do so. If there isn't one close to you, maybe just make a phone call to the nearest one you can find.
Assuming that doesn't work out, it's possible on some Nokia phones to change the product code, so that you can update a different firmware variant. you need a special software called NSS to change the code, and the usual Nokia firmware update applications from Nokia.com for your phone. An example for how to do this for the 5800 is here: http://www.techhail.com/mobiles/procedure-to-change-product-code-on-nokia-mobiles-like-n97-and-5800/2830
Changing the product code probably voids your warranty. Also I don't know if your particular device supports firmware update, or if there is a Hungarian variant for it.