I doubt there is a "cheap" way.. The music files are connected to ingame events
You might try to copy some files to waband/music and edit music.txt in warband/modules/crpg
I think those with the number 7168 7168 are the battle sounds and therefore used in crpg so you could try to overwrite them with your music. So convert them to ogg files (dunno if really needed) and rename them to fight_1.ogg fight_x.ogg etc. overwrite the existing ones and add them in the music.txt.
Cant test myself as I am currently sitting on an old laptop.. the cheaper way is using winamp^^