At the character selection screen quickly press (on the d-pad) L, D, D, R, L, U, L, U, R, D. If entered correctly it will say, "All to easy". Then pick any player and it will be Exor.

P.S. One problem is it only allows Exor once after the Character selection screen and the person you chose will be who you are. If you lose and enter the code again it will still work.