Talk to him?
If he really is a "star developer" he'll take note of what you say.
It may not change him overnight but it might be that he is just completely unaware that other people dont get it quite like he does.
Edit:
It's probably a bit late to change now, but more information is needed in working out a solution. It's impossible for anyone here to actually suggest letting the guy go based on these points alone. If you've been telling the guy every day for the last year that he needs to change or he's out of here, then you can let him go. However, I see no evidence of that.
A brilliant developer can be taught to use source control, comment and document. If you spend the effort here then you truly will have a star developer.
