Press Start to pause game play, then press A, B, Down, A, B Down, Left, Up, C.
Collect the extra life at the far right end of the first level of the museum. Jump onto the rising platforms. Jump back down when reaching the third platform or when the screen scrolls up to collect the extra life again.
Reach the second platform at the top of the level. Move off the left side of the screen and fall in a straight line to collect three extra lives while losing one life.