DWI is not a music file, it is a text file that is used with the program "Dance With Intensity" (a Dance Dance Revolution simulator). The file basically tells the program what steps to display and where to locate the mp3 file of the music to be played along with the steps. Since the song you're looking for does not appear on any official Dance Dance Revolution mixes, a DWI file would only exist if someone created one with their own original steps (like for a DWI contest or the like). DDREI (
http://www.ddrei.com) holds DWI contests regularly, so once the next entries are put up for download, you could search through the entries and see if anyone has used that song. It's possible, although it's a long shot.