What area do you live in?
The most important things to remember when shaping undesirable behavior is you have to make the result you're looking for easier to accomplish than the negative behavior, and sometimes him getting angry might be because your reaction to that behavior is fulfilling some basic need.
I live in Florida now. Sadly we missed out on any kind of early intervention because he was never disruptive and was passing most of his classes so I was given the runaround for so many years. And now I have an adult child. I've learned to "stand down" when our conversations have become heated - but he's not learning from me anymore he just thinks I'm stupid. So I need to get him out and more socialized. Job training and placement would help his self-esteem and make all the difference in the world - at least I hope so. I've approached him about speaking to someone at the local state health and human services office...I don't know how long it's going to take him to come around but I've planted the seed and I know he's thinking about it. I guess I need resources for me...and it's frustrating because I'm on the scale too!
The particular non-profit I work for specializes in helping people with this exact sort of thing. Unfortunately we are focused in our local area.
Not sure where exactly you are located but this website might lead you in the direction of some organizations with some resources that could help you.
http://www.arcflorida.org
I hope this helps a little. If not let me know and I'd gladly do some research for you!