Actually, to be honest, and no offense to Mike, I think if he IS to be involved, I'd rather see him as just a session drumming more than anything, kind of like with OSI or more recently, A7X. Just comes in, learns the songs, lays down the drum tracks - in, out, one week or two... That way, if needed, they could just sub another drummer for him if any of the material gets toured - ya know, no REAL huge commitments.
-Marc.