Don't play that game
As Kevin Drum points out, the operative strategy for dealing with the Plame Affair is to obscure the issue and make is seem like it just a partisan fight over something of little consequence. Throw up so much mud that people will lose sight of what the fight was originally about.
We must not play that game.
As Kevin urges, keep it simple. Remind people that no one from the White House has denied that someone in the administration blew Valerie Plame's cover (a blatantly illegal act). Their response to the scandal is to turn the tables and attack the accusers. If there wasn't substance to the fundamental allegation then they would outright deny it. They are not because they know that it is substantial.
Stay on target.
(Another useful talking point: point out how so many people were outraged by allegations that Clintonites were trying to smear Monica Lewinsky. Yet the Republicans are openly urging a "slime and defend" strategy for dealing with Wilson and Plame. Ask a Bush defender to defend that little bit of hypocrisy.)