Press & Hold L1+R1+Start+Select At The Main Menu & You Should Hear D'arci Say "your under arrest" Now Select New Game & On The Next Screen, You'll Notice That Every Level In The Game Is Now Selectable.

Now Save Your Game So You Don't Have To Do This Cheat Over & Over Again.

To Disable This Cheat Just Press & Hold L2+R2+Start+Select At The Main Menu.