Chances are that you will get better results if you convert the mp3's to .wav's and then rip them apart but if you don't want to do that, there is a program called pc-dj that does something like that.
Try either soundforge (which I believe only allows you to do one wave file at a time (or two if in stereo) or try n-track with is a recording/editing program.
try www.goldwave.com
their demo is fully functional ... (you get a limited number of mouse clicks before it gives a "register now" message)... plus ... i fyou register it's only like $30.
GREAT program ... easy to use and it works very well.