disgraphia and OCD

What do you do with a student whose writing output is minimal in every situation because they obsess over every curve of every letter?  This is a student who clearly falls into the Asperger's category, but the difficulty with writing adds another layer.  He does better writing text on a computer than with a pencil, but what about writing out steps for a math problem?  He is gifted when it comes to doing math in his head, but in 7th grade is already beginning to hit the limits of what he can do in his head.  He needs to write out the steps but refuses or works so slowly that it's counterproductive.  I'm open to any ideas!