Extra Lives
Go to the Options screen and highlight "Rest." On Controller 2, press Up, X, Left, Y, Down, B, Right, A, Up, and X. You'll hear a tone when you press X the second time to let you know that you now have nine continues.

9 Continues
Go to the Options screen and highlight "Rest." On Controller 2, press Up, Up, Down, Down, Left, Right, Left, Right, B, A and you will hear a tone. Use Controller 1 to select up to nine lives.