I actually spilit my speaker cable(the one goes in your computer) and recorded some music via audio input.
Its like it records whatever music is playing on my computer using "NERO WAVE EDITOR" .
It works great and now why did I record any music?
I got sick of marvel vs capcom 2's fruity music and I recorded some old school street fighter and samurai music and now marvel vs capcom 2 plays better then anything

.
PS:NO !, I am smokin crack again.

Its possible,I found a guide online somewhere "how to change dreamcast game's music"