Hold A and B and C and Start at the same time at the game menu screen until the team selection menu appears. The EA Sports and THQ Inc. teams may now selectable.
This code only works when you play against the computer, and they only have 2 active goalies. First, you must injure the opponents starting goalie. This works best by running into him many times. It would be helpful to turn penalties off, so you don't get called for interference. Once he is injured, score enough goals for the computer to switch goalies. When this happens, one of their defensemen will be the goalie, but he won't be replaced. The game still treats this as even strength, so icing still applies.