WIth this code, in very few places in the game, if you hold down R+L, it will cause the game to freeze> The times you need to press both buttons at the same time & the places are few & far between, so it shouldnt be a problem.

With this code, Pause your game first, do not press the buttons while the game is not paused, it could cause it to freeze, then Hold R Trigger first, then Press Select while holding the R Trigger to bring up the Level Select Menu.