My boys are the same. We were at the end, didnt know what to do with them.
We have bought "the kazdin method" book/dvd and its great. Its a reserach driven method. Not somebodys ideas.
Its changed our focus to the positive things our boys do, and their focus too. I can highly recommend this programme. I havent even finished the book but the results are showing. We still have melt downs but its ok now.