If the SPAMALOT men are all considered supporting, which I highly highly doubt, then Cheyenne has a very good chance. If not, I can't see a nomination for him.
I thought Cheyenne was fine in ALL SHOOK UP - not bad in any respects, but not amazing - but that's the material's fault, not his. Many great actors have been able to rise above their terrible material and shine, but Cheyenne just doesn't command the stage like I had hoped. I would nominate him over Daniel Davis, Gary Beach, and Tim Curry in a heartbeat - but certainly not over John Lithgow, Norbert Leo Butz, Hanz Azaria, or even B.D. Wong.
"If you are going to do something, do it well. And leave something witchy."
-Charlie Manson