If they haven't started talking with a team in Japan about a possible purchase of Dice-K, I'd recommend doing that as soon as tomorrow's game is complete. I don't know how it would work, but at this point, I'd take just about anything in return, especially money that could go towards off-setting what's left on his contract.
Selling him to a team over there allows both sides an graceful departure from each other, as the Sox would get something in return (as opposed to nothing if they DFA him), and Dice-K would be able to return home to a place where his style works and he can pitch well in front of his fans.