Here's a Halloween PowerPoint slide for the song, which is in Jeff and Randy's GamePlan. See their book for the melody and their complete lesson plans for this song. The song is either in the 1st or 2nd grade curriculum. I don't have my books at home and don't recall at the moment. I'll try to remember to edit my post later. If you don't already have any of their GamePlan books, I recommend purchasing them for well thought-out, high quality lesson plans that the students enjoy.
I set up four instruments in a square and let the students line up behind each one. I sat in the center, so I could reach all of the children. They played a steady beat bordun on D and A. After they played, they rotated to the end of the next line. We continued until each student had played all four xylophones. Students in line continued to sing & pat the beat on their thighs.
Looking for more Halloween fun? See some of my other favorites here and here.