At the title screen, enter the cheat to view the ending a total of 3 times, then start a 1-Player game. During the game, before drawing your tile, press Start to enter the tile editor. 16 numbers will be displayed on the screen: you can use the D-Pad to select any of them and A/B to increment/decrement them. These numbers represent the custom tile queue which is used to select the next tile.

In order to use this in Simple Mode, you must enter the credits 254 times. For a 2-Player game, you need to do it 255 times.