P.G.
ADD: Have you talked to him about it? Autism is something that's a part of him and that he'll be managing different aspects of as he grows up. Perhaps asking him to help YOU might frame things differently. Just a thought.
ORIGINAL: Has he been evaluated and are they providing any speech or OT for him? My son is on the spectrum, in 2nd grade. His issue was more with speaking out of turn than to get attention. He had speech (for pragmatic language) a couple of times a week, and they would also work on taking turns, classroom behavior, etc.
Our kiddos don't have all the behavior filters in place, so it is harder for them to manage behavior. Executive function, which is this skill, is a challenge. It can improve, but it takes extra work and help.
Also, one thing that helped a lot was a wobbly cushion (not sure which one, but it's like the gel cushions - http://funandfunction.com/catalogsearch/result/?q=seat)
My son got out of his seat several times a day (he wasn't really disruptive, but he couldn't sit still) until the school got him one of these cushions. It made a HUGE difference. If your son is a sensory seeker, request the school try this.
Also, visit Karla's ASD page on facebook. She may have some ideas on her site. She's an autistic adult at Intel and she does some IEP consulting. You might even be able to post your question on her page.
Visit www.autistikids.com - there are a ton of links on there to autistic bloggers. You may find some parent bloggers who can help with this as well. Feel free to PM me if you like.