See above, is anything like that possible without an SDK?

I was just listening to The Eagle sountrack and some of the tracks felt like straight out of the The Witcher (http://www.youtube.com/watch?v=LaaUlhje6oM, http://www.youtube.com/watch?v=Y8AHdSU7t0o). I though it would be great to add them into the game to give the music more variety while also altering my experience a little bit.

Would anyone know how to do that?

Somewhere in the depths of this forum there's a tool that unpacks the music files. Theoretically, unpacking and replacing the music with new songs (renaming the new songs with the old songs' titles) and repacking the archive might work.

But that's just a theory, and it would be a lot of work even if it was viable. For what it's worth, I'm pretty sure the music is in the .fsb files in the CookedPC -> sounds -> music folder.

The music is kept in The Witcher 2\CookedPC\sounds\music, and using a program I found linked to in this topic, it is possible to extract all the music files and even convert them into .wav. I have no idea if there's a way to replace the tracks, and then repack the files back into the .fsb archives, however. :/