Possible 2 Map Image Element 2 Sound?

I haven’t had any trouble mapping an mouth shape elements that I’ve created to the Toon Boom’s mouth shapes. However, I was wondering if it’s possible to map image (raster) mouth shapes to Toon Boom’s mouth shapes. I saw the vector example in the help manual’s tutorial area, but I didn’t see a tutorial for linking up raster mouth images. Any help on this issue would be greatly appreciated. Many thanks.