Nurtured Heart Approach - Transforming the Difficult Child workbook. Lots and lots of praise for every second he is breathing and not hitting - I exaggerate but the point is make the good behavior the focus and maybe he may like the positive attention instead of negative. Do you have any reason to suspect ADHD? It seems that he has impulse control issues in several settings. My DS has had similar issues and he has responded to the NHA - the timeouts are as La Texican says more about disengaging to diffuse the behavior you don't want.
Good luck.
