[falling U P]

I know that this is the opposite to what everyone else has been asking for lately (extracting vocals so you can make instrumentals/vocal cuts) but I was wondering if it's possible to extract the background music to a song, in order to KEEP the original vocals? Not sure if that makes any sense but like... I've been wanting to mix songs and I want to get the vocals from one song and mix it to beats that I've made recently. Like for example, if I can have a song (the words only) with a 2pac beat. Hopefully that makes sense. But first off, is it possible? And if so, what's a good program for it?

[apparition]

please see this related post about removing vocals (same thing).