[XeTeX] How to embedded audio files in PDF output

[Andy Black]

I've seen in the archives that some folks have had success embedding 
audio files via XeTeX in the PDF output.  Unfortunately, I did not 
understand the exact code needed to make it work (since the one I saw 
was for movies, not sound files).  Could someone please supply an 
example of a \special command that makes a clickable sound file activate 
in the resulting PDF file?  An example for a .wav file or an .mp3 file 
would be great.

Thanks,

--Andy