I have no idea about Acid...
It can be done with an old-fashioned mixer, a polarity-invert cable, and panning knobs.....
Note that whatever mechanism you use - it has limitations - all the stereo effect remain intact, and you lose any phantom-centre information such as bass, kick, and snare... (although some plug-ins account for frequency make the change frequency-dependent)
It's NOT going to turn a song into an instant Karaoke track........
Bruce