When screen pops up right before you start the game you have three boxes you can change for code input. Square changes the first box, X (Some report as Triangle) changes the second box, and Circle changes the final box. Example for code 1-1-2- Left you would press Square, X, Circle, Circle, D pad Left

Long Bat 0-0-4 Up
Wiffle Bat 0-0-4 Right
Mace Bat 0-0-4 Left
Rubber Ball 2-4-2 Up
Maximum Speed 0-0-3 Left
Maximum Power 0-3-0 Left
Maximum Batting 3-0-0 Left
Big Head 2-0-0 Right
Small Head 2-0-0- Left
Infinite Turbo 4-4-4 Down
Tourney Mode 1-1-1 Down
No Fatigue 3-4-3 Up
Roman Coliseum 3-3-3 Up
Rocket Park Stadium 3-2-1 Up
Pinto Team 2-1-0 Right
Todd McFarlane Team 2-2-2 Right
Eagle Team 2-1-2 Right