It's actually very simple: translate all the voice acting into your language of choice - let's say Norwegian. (Probably dumb the vocabulary down a bit.) Now add subtitles.
You're done. Go play the game. You'll absorb the language as you play, and because (unlike a film) you'll hear the same phrases multiple times, it'll actually sink in to a useful extent. I've only played about 20 hours of Skyrim so far, but I'm pretty sure if I was playing the subtitled version I'd already be able to say "Are you looking to defend yourself, or do some damage?" in Norwegian.
(Of course, I'd still have to add modern language to my knowledge after 200 hours, but hey, it's easier than learning the entire grammatical structure and all verbs.)
For a much more effective but much more offputting version - don't have subtitles. Have a few characters who can speak a bit of English, but have most of them only talk in Norwegian. You'll need to customise the dialogue a fair bit too so that the player doesn't miss important bits (essentially, have the NPCs periodically stop and say "WTF? Are you stupid? THERE'S THE GODDAMN DRAGON!"), and probably have the usual range of dialogue options - in Norwegian - plus a standard "I'm sorry, I don't speak Nord" which will get you all the really essential stuff.
That would be very, very hard to play - although surprisingly immersive if you're playing a non-Nord character, particularly if the other non-Nords were the characters who were likely to speak your language - but would definitely teach you the language.