How do you get the pigs to get off the mumbo crates on banjo kazooie nuts and bolts?

Oh and everyone remeber that pig ghost, which stopped us from getting that Mumbo Crate in the demo? According to the guide, to get the crates, you must complete the Grunty challenge in the Terrarium of Terror. Afterwards you will get a horn that you can use in Showdown Town to get rid of the ghosts.