[MPowell1944]

1. Extract Pak0.pk3 using http://www.winzip.com]winzip.
2. Open notepad and open up the file mohdm3.mus in Pak0/music folder.
3. At the top of that file, it will name the .mp3 that it uses for the ambience.
4. Find that file in your /main/sound/amb_stereo folder.
5. Now just copy n paste the music you want to use and rename it to the ambience file name. Make sure to backup the original ambience file first of course.

Its that easy. Lemme know if you have any other problems.