This should be a simple edit. I can take a look at it when I get home this evening.
The easy way would be to simply set the character's face graphic to the character's sprite, but obviously if you need to use the character's actual face graphic for messages or anything else, that won't fly. If you can do this, you'll need to rename the sprite graphic to have a $ in the beginning (for example, $alex.png) for this to work.