Yes, it's possible. Technically.
No one knows how to do that yet, though.
Yeah seems like no one ever tried to work on audio seriously...
That's sad because being able to customize audio can be a very big step in modding of the game...
I managed to gather some information about game audio system, things like the exact xna version that the game used and even a simple tool to export and rebuild audio archives.
If anyone is interested we can start work on it together...
Any slightest information and things that maybe someone know can help as well...