How do you prepare a team to go for the kill in a close series?
For me, it starts with mental preparation. Forget the negative stuff, all the things that went wrong and treat the game as a single, must win game. If you can match the opponent's desperation, you've got the mental edge because you're not actually fighting to survive, therefore you can think clearly.
Early on in the game, set the tone with a big hit or a scoring opportunity on the rush to keep the D honest. Make the goalie move if you get early possession. Break them down with speed and strike early. Plant the seed of doubt. We've had that done to us at least 1000 times before, we should know how to do it to others.