I just don't remember anybody in the Admin stating that Tenet said it was a "Slam Dunk". The only time I have read or heard it other than in forums is in that book.
I can see how it could be taken out of context. Either way saying, "It's a slam dunk to get people to buy into the war." or "It's a slam dunk that they have WMD." both are pretty bad.
He also stated that the CIA thought he had them.
I have heard Cheney say it plenty of times. In fact on televisoin last night they showed a clip of him saying it on hardball.