i've tried it before. it works really well depending on the song. basically always makes it sound crappier.
i forgot how i did it, but it involved a lot of phase inverting. basically i isolated what was on both channels (lead vocals are usually dead center) and then flipped the phase of it.
it was something like...take each channel (left and right), flip the phase of one, run them dead center, and export that. bring it back in and then flip the phase of that wav and mix it with the original.