Sent in by Link at The Unofficial World of Nintendo!!!
On Circus Train, look out for the skull headed biker, and the metal bars.
The only guys that jump over those are the blue thin clowns.
At the Options screen, use Controller Two to press Up, Up, Down,
Down, Left, Right, Left, Right, B, A. If you performed the trick
correctly, you'll hear a musical sound. Now go to the LIVES
option, and give yourself nine lives!
When you get ready to start a new game, go to the option screen
and highlight the rest option. On Controller 2, press Up, X, Left,
Y, Down, B, Right, Up, X. You should here a tone. When you get a
Game Over, you will have nine extra continues.