Really wish I knew how to deal with his temper...

I can't talk to him or I get "you're mad at me" to which I've been ignoring. I can't try and redirect him or I get a huge screaming fit because he can't get his way. I can't put him in time out in his room or he kicks the door screaming and carries on for over an hour. No tears...just total production. He is truly our head-strong drama king. The behavioral therapists suggested that we only praise the good behavior and we ignore the bad behaviors. That upsets him and he will continue to turn it up until I eventually have to acknowledge him. He's been a handful all day long before therapy and during therapy. He's in and out of the bathroom as he's got to see what the therapist is doing with the other kids or find a way to get back to being the center of attention. I put him down for a nap in his room after lunch and that pissed him off and he screamed for 45 minutes at the top of his lungs...finally started kicking his door saying he had to go poopy. I walked him across the hall and told him if he was lying to me he was in trouble. Sure enough, he didn't have to go. It's hard to tell with him as he does go to the bathroom quite a bit....but this time it was total attention seeking. Put him back in his room and he continued to scream for another 30 minutes at the top of his lungs. Wakes Baby T up from her nap and then he calms down. I hear the door open and I catch him coming out of our bedroom. He runs for his room and I ask him what he's been into. The tv. I ask him if he's making good choices or bad choices and he says bad choices. He gets put back in his room and he's screaming at the top of his lungs yet again. He can tell me that he knows that he's not supposed to be doing certain things or not touching things and yet he continues time and time again to make the bad choices. Sometimes he honestly makes me feel like I'm a failure as his parent. I want to enjoy him and be proud of him. I love him to death, but I just don't understand why he can't make the right choices. It scares me to think about what he's going to be like as he gets older and can really get himself into trouble with wrong decisions in life. I will support him and love him no matter what, but I really don't understand why he can't seem to make the right choices.