Paul,
This is actually fairly easy to do using registrations. It takes a fair amount of preparation, but if you have the ability to memorize the words and chords, it's just a matter of setting up the registrations and pressing a few buttons.
Good luck,
Gary

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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)