I have done that before and it worked quite well. I just don't know which program I used. It's been a while.

I was making an uncut Version of "Lilo & Stitch" (it was cut in Germany to get a G-rating). I found the missing dialouge on a radio play CD. The problem was, they used different background sounds and music as used in the movie. I found a program (I don't know what it was) which could suppress the background and "raise" the speech to the foreground. Not all noise was filtered, but in the final 5.1 mix it was hardly hearable. This time it's a little easier. Han's line "I bet you have" was dubbed new in '97 for the SE in Germany. I want to put the old line back in the 5.1 track. The problem is, that the music is too loud, suddenly it comes from the center, while it's supposed to come from de L/R-channels. The background noise on the stereo-track is the same as in the 5.1.

Does anyone know a program which can do that? And how?