I know it's been a couple of weeks since you posted this, but I'm somewhat new to this forum, too. I have a 10yo son with NF1, also diagnosed w/ ADHD, and now we're suspecting Asperger's Syndrome. He,too, can be very explosive. He needs to have a specific schedule, etc. or the smallest thing can throw him totally out of whack. We don't think he has ODD because he seems to be able to control himself with authority figures in school, church, etc. But with his parents (us!) he can really lose it. It can be so frustrating. Any change really sets him off (time-change, season changes, vacations and holidays, etc are very difficult for him). We didn't always realize that. But now that we do, it's somewhat easier to deal with and be more understanding. He just can't help the frustration he feels. It's also extremely important that he eats on time and gets enough sleep (difficult, because he has pronounced sleep issues.)
I just ordered the book "The Explosive Child" by Dr. Ross Greene. It's supposed to give a practical, comprehensive approach to parenting a child with behavior challenges. You can go to www.explosivekids.org
for more information.
Hang in there...you're not alone!