With the exception of the french knots around the eyes, the white parts are done with glow-in-the-dark-floss. (It's rather slippery stuff, and I didn't have the patience to use it for the french knots. It would've looked so cool, though.)
I tried to get a picture of it 'glowing,' but it just wasn't in the cards. :(
See this pic to get the details on the stitches I used.
From the book Embroidered Effects by Sublime Stitching.