No I haven't seem to be able to find that one. It is one of my favorite shorts from disney. The only thing I know is that the song was written by the legendary Paul Smith. Hopefully we'll find it someday. Ears Hopin'
in the worst case you could rip the song from a DVD. At least in Germany the short has been released on several Disney DVDs as bonus material.
Which brings me back to an old question: I know that I can rip the sound off a DVD while it runs at regular speed, but is there any software which would allow me to rip the soundtrack of a DVD at higher speeds, such as done for music CDs??
"Trick or Treat" was recorded by Mouseketeers Karen and Cubby for an album called HOLIDAYS WITH THE MOUSEKETEERS (Official Mickey Mouse Club Records MM-22). The LP was reissued on the Disneyland label as HAPPY BIRTHDAY AND SONGS FOR EVERY HOLIDAY (DQ-1214). The latter LP should be easy to find on eBay.
The soundtrack version of "Trick or Treat" turned up later on another Disneyland LP called TRICK OR TREAT (1358) , which also included an edited version of THE HAUNTED MANSION LP. Portions of the song appear on side one, though it is not played completely. None of these albums have appeared on CD, yet.
If you are looking for Disney-related Halloween material on CD, I recently discovered that Bing Crosby's single version of The Headless Horseman is on a CD kid's compilation called Big Rock Candy Mountain (you can get it at Amazon).