Bob, you cant get a copy of that song because it doesnt really exist. It was just made for the movie, and isnt in the SDTK. The persons who performed it have never made any other recordings of that tune. So unless you get a sound grab from the movie..that is the onyl way you can hear that song. Also the band is Bang Wa Cherry.
Edit: ok i lied. Go here:
http://www.icomic.com/gallery/categories.php?cat_id=27