At the options screen, press Triangle(2), Circle, Square, Triangle, Circle, Triangle, Square. If you entered the code correctly, a level number selection will appear at the bottom of the options list. Now any level up to 50 may be selected in easy difficulty. Any level up to 75 may be selected in normal difficulty.
Enable the "Cheat mode" code and start a game. Then, pause the game and press Triangle.
Enable the "Cheat mode" code and start a game. Then, pause the game and press Square.
Enable the "Cheat mode" code and start a game. Then, pause the game and press Circle.