Sometimes we all just want to scream our heads off, and get rated on it.
http://www.youtube.com/playlist?list=PLXGBPIXPEUMLqoYD2rOSnA75p6D-ucCQ3
Heh, we got these songs already.
Given the nature of these performances, it won't be possible to pitch them. (way too much variance)
So, just play the instrumentals and scream the lyrics out. I don't think your score will really matter.