I could perhaps attempt to make some sort of loop of the drums and maybe bassline from the karaoke.. and someone else could do the guitar. I dunno, I'll fiddle around with it later but I can't promise anything.
EDIT: Uh, why do I even open my mouth? This is impossible. I suppose with enough patience and the karaoke, extended version, DTS tracks and such, someone might be able to piece something together.
Dude, just sing with the karaoke.. that's what it was made for :-P