Press Left, Triangle, Right, Triangle, Down, Circle, X at the main menu: A message will confirm correct code entry. If you are taken into a menu, just back out and start again. All of the previously locked bonus materials will now be available. Alternately, press Left, Triangle, Right, Triangle, Circle, X at the main menu.
Fire Reaver
Pause game play, then hold R1 and press Down, Circle, Triangle, Up, Right, Circle.