Diet! Feed him foods from natural sources only. No colourings or additives, not too much sugar, no sweeteners...nothing artificial! Chocolate and Coke (and other fizzy pops containing caffiene particularly) are a 'no no'.
Colours! What colour is your living room? His bedroom? The clothes that you put on him? He needs to be surrounded by calming colours; pale blues and greens...never red!
Toys! One toy at a time; kids can get overwhelmed with too many things, too many options etc. Books and Art are always good. Too much T.V. or computer games etc. can send anyone round the bend, so that's also a 'no no'.
Speak calmly to him and act calm around him. Children copy.
Massage can work wonders. Before he goes to bed, play some soft calming music and gently rub his back for a few minutes...
Routine is also important. If you give in to his screams, then he knows that he can get his way by acting up. If he gets nothing; no attention (neither positive or negative), eventually he'll give up.
I know it can be hard. My daughter used to act up dreadfully. It got to the point where to get my attention she would throw herself on the ground and bang her head against things; because I couldn't ignore that (one time I didn't get to her in time and she split her head open so bad that we ended up in hospital!);She's 7 now and we don't have as many outbursts. She still can only have small amounts of chocolate etc. and I still have to work with her, but we're getting there.
When she becomes uncontrollable; which does still happen on rare occassions; I will force a hug on her. I hold her tight and tell her that I love her, 'calm down sweetie, I love you, I only want what's best for you because I love you, so let's calm down, so we can sort this out'...I can get kicks, bites and allsorts, but she does calm down eventually. And once calm we will talk about how silly and unnecessary the outburst was. She will apologise, we'll hug it out and we will decide on a punishment together.
The most important thing is to stay calm (behave how you want them to behave).