Instructions
Beat the game. You'll have to do this before anything else.
Collect 90 "Jiggies." These are collectible tokens located throughout the game.
Go to the Terrarium of Terror. Win the mini-game and you'll be given a horn.
Honk the horn at the ghosts sitting on top of various crates you find throughout the game. When the ghosts leave, open the crates to find super parts.