itunes could never do it, here's why:
an audio file is a single thing, and the components of a song (the vocal, the drums, for example) cannot be seperated out from that single file.
there are tricks to minimize the vocal, reversing phase for example, (such tools have been around for decades),
but basically, it can't be done.
the multitrack files that make up that file, ie the pro tools files, are what you'd need to get whay you want.
still,
maybe someone else here can suggest something else...?