Al,
I have done something similar by taking two jaws off the chuck, using a square block in the chuck, and turning the cup in the part of the block projecting from the jaws. To get the offset after turning the cup. loosen the chuck and slide the block sideways in the two jaws and retighten the chuck. I used #3 profiled jaws when doing it.
Yes, use a large cup, and keep the rpm's down.
Was Christian Buchard the orginator of this? Seems like he was.