> > > > No, the audio is not in .aud format
> > > It needs to be.
> > I successfully converted a test mp3 to aud and and named it justdoit.aud (same as an existing song) and removed the file in the mix file and inserted the new one.
> > The game supposed justdoit.aud was the original one so it named the song 'Just Do It' as the old one's name was.
> > Now, if I'm about to insert a file and not overwrite some other, it wont show up.
> > I beleive I must hack the binary or something to make it apply the new song...
> > This is the new problem :]
> But if you first delete the file and then insert the new version, it works?
Yes, It does, I've downloaded a 'star-wars music pack' for the game, I'll have a deeper look into their mix file, in the description they've also deleted the music then inserted... 
> > > > I tried inserting a file (with XCC MIX Editor) in scores.mix (where the music is) file, then I tried closing the tool and opening it again and open the file but I didn't see the file anymore
> > > Did you click Save?
> > I probably missed that part 