My only advice is get him out as much as you can - no matter how much he looks down his his at you (or up his nose, up at you!).
My oldest son is an Aspie child - and can get manipulative - it is easy to feel bad pushing a child with issues - but we are doing them no favors by not.
If you can I suggest daily walks. Every day. They need not be long, but he learns he has to - and it builds strength. The computer will survive for an hour without him. I am laughing becuase my oldest is the same way!