Begin the game, and as soon as you are able to move the cursor, hold Up+A+C+Start. You don't have to press them at the same time, but they all have to be held. It's easier to hold A+C first, and then the rest, that way you won't accidentally end your turn. Now, you probably accidentally opened a menu already, so just press B to get out of the menu, and if you are still holding the buttons, a tune will play and you'll automatically end the stage.
At the title screen, after passing the PUSH START BUTTON option, press C x 29 times. Then hold C + Start.