Actually two of the families I baby sat had a kid just like that. One of them, Anthony, actually DID act (when he was about 8) in a HBO movie. Both kids were homeschooled and did well.
I think the best thing to do is keep him involved in community activities (such as an acting class or something), but these kids actually do really well in homeschool enviroments - they just need to be kept in focus and possibly given small bursts of work, like "work on this for five minutes, then you can have a five minute break."