Antares (the company that invented the Auto-Tune software) used to make a rack mount AVP-1 unit that would do pitch correction keyed by MIDI, and I think that several of the newer 'harmonizer' modules can do MIDI keyed pitch correction. If you are looking to do this live, you might want to take a look at some of them.
_________________________
An arranger is just a tool. What matters is what you build with it..!