As for Chris Reeves, he was great at the role and is quite the superman in his own life battles.
A guest appearance would most likely be on the cards as he did in Smallville.
I think they should use CG, and magically put Reeves back into the role of superman. If they devoted all the processing power used in Shrek2 just on building the Superman character, and everything else was live action, it would probably look great, and it would make him having super powers more believable.
