Aw, this breaks my heart, such a tough age. I would start with scouts, I don't know if they already have a standard 'curriculum' and program, but if they have some flexibility, maybe ask the leaders to work in some social skill sets, this way he could use them in action.
Otherwise I would read up on the tween years for boys and start there. Ask him questions to determine his issues and identify where he needs work. Role play with him while teaching him how to handle different situations. The best thing you can do for him is give him practice before he's in the real deal.
If he really needs a lot of help, maybe look into occupational therapy for him or work with someone who specializes in ASD. Good luck to you and your little guy.