it would probably take a while. i learned what german and russian (not very much at all) on my own, and it takes patience and constant environment. i would always listen to german bands (like rammstein and megahertz and such) to immurse myself in it, and if you can be around it all the time, it makes it easier. like spanish, which im taking now, i can just walk out the door and be surrounded by it :P (stupid retards blaring latino music until 3 am!!! grrrr) and my bf's familia married into mexicans from l.a. (:\ double no-no spanglish PLUS l.a. accent.)

in short, surround yourself in the language and culture and you will learn faster

edit: and learning it with a friend helps you guys learn faster and you teach each other. me and amber learned together