At the main menu, hold Select and quickly press Triangle(3). Then, press Square, X, Square, Triangle, X, Triangle, Circle, Square. Begin a new game, then hold Select and press Left or Right at the mission introduction screen to choose a new starting level.
At the main menu, hold Select and quickly press Triangle(3). Then, press Triangle, Circle(2), Triangle, Circle, Square, X(2).
At the main menu, hold Select and quickly press Triangle(3). Then, press X, Circle, Triangle, X(2), Circle, X, Square.
At the main menu, hold Select and quickly press Triangle(3). Then, press Square, Triangle, X, Square, Triangle, Circle, X, Triangle.
At the main menu, hold Select and quickly press Triangle(3). Then, press Triangle(2), X(2), Square, Circle, Square, X.