This a post I have copied and pasted that I made on another thread..
My son is ASD (Autistic spectrum disorder) ADHD, has Anxiety, learning disorders, speech and language disorders the list goes on.
When I want him to stop what he is doing, I hold him by the shoulders, so he is still, I make him look at me (eye contact) I give a simple direction, followed by a punishment if he doesn't listen.
Example... David, Stop shooting your gun in the house, ( I then make him repeat what I said, I then ask does he understand what I said) then I say " now if you don't stop shooting that gun in my house I will take it off you for 2 sleeps (he doesn't understand days of week and time etc, but understands sleeps).
If 20min later he shoots the gun in my house, I will hold him, make eye contact and ask him and I will say " didn't i ask you to stop shooting your gun in my house" he will say " yes" I will say " well I said if you did it you will lose it for 2 sleeps, I then remove the gun"
At first you get tantrums, throwing things about... I used to ignore that and now he is just great, I ask him to do something and usually he does it first time.
Consistancy is the key.... and don't through out empty threats, if you say something follow through with it no matter how many tears they give you and how many sorry's.They need structure and boundaries they don't need excuses and people letting em just get away with things.
My son also goes to a Mental Health Clinic weekly for his disabilities and it has helped a great deal, so if your struggling with getting your son under control and his behaviour is having a negative effect on your family, i would look into some kind of outsourced support who specialize in children with these sorts of disorders.
Good luck
Also wanted to add that my son is now 10yrs old and with firm discipline and structure they do get alot better as they get older. You need to remember that your NOT the only one frustrated they are frustrated also. I rememeber watching my son struggle to tell me a story, he had trouble just trying to find the words ( he would get them wrong, like oh mummy this is sour, meaning HOT (spicy)), and when they hit school age you will go through some really rough years because it's then they REALLY notice they are different, but as long your rules stay the same and you support them as the years go by they adjust and life gets a lot easier for you both. My son really struggles at school and is why below the other children but he is alot happier within himself these days.
My son is in a main stream school but is under the special needs department so he has one on one time, a mod program and a teacher aid in the classroom at all times (the aid usually has about 3 special needs kids)