This is such a frustrating issue because the kid who is sensitive and is having difficulty with impulse control really looks like a "naughty" kid, and can be VERY frustrating. Even when you know such kids well, they can be really frustrating.

He might be a little young for these but there's no harm in trying something, right? There's a very nice little series of books called "What to Do Guides for Kids," one in particular that's good is "What To Do When Your Temper Flares: A Kid's Guide to Overcoming Problems with Anger." They're really nice to read and work through with kids; I've learned a lot about myself in them! Otherwise you're on the right track, sometimes you just have to try some different therapists until someone has some ideas you can use.

Best of luck to you.