is there anyway to add my own music into BG? i want to see how some blackmetal fits with the end battle with Irenicus
I mean, WHO could resist that?

The musics that are in the game are in ACM format; http://iesdp.gibberlings3.net/ieformats/acm.htm

Now, that points to a russian site with an ACM converter, but I can't read russian :-(

Thanks...All i have to do now is to find a russian, beat him down, and force him to translate

See this article by idobek.