Start off in hand- get the horse to the point where they'll respond to whoa/walk on/trot just off voice cues and they respect your "bubble" of personal space and won't invade it. Whoa is especially important. When they've got that down, I would start out actually lunging in a round pen if you have one. I would recommend Meredith Manor's article on lunging, it explains everything better than I can.
First of all, you can't make more than 2 sessions a week, you can start by 10-15mn, it is enough. Don't do small circles, it is bad for the hock.
You have to always be behind your horse (in the middle of the circle) to make him move forward, at his shoulder to make him stop or slow down and stay in the middle to be neutral.
If he is not used to it , put him on a lunging ring (this way he cannot escape to the outside of the circle)and if he comes back to you, push him with the lunge or the lunging whip.
Always be careful (wear your helmet and gloves) especially if he has temper, what do you mean by "horrible manners"? If you don't feel secure at the beginning, ask your monitor to lung him for the first time so you'll see how he reacts.
I hope i could help you, good luck :)