Basically, what you need to teach your guy is to move his front end out, and then the rest will come into place.
To do this this, put your horse in a basic halter & lead rope. First teach your horse to move his head and neck from left to right. To do this, reach out sideways with your right arm, rope slack. With your left hand, have the tail end of the rope and quietly flag it on the other side to I nfluence him moving away. Once he responds, immediately put down your arms. Do this until you can influence him to sway his head and neck from side to side as you ask. Then you can start to ask him to move his feet. Same concept, but this time you'll twirl the tail of the rope at his shoulder, other arm outstretched until he takes a step to the side with only his front end. DO that both ways until it gets easier.
Then you can start walking into his throat area, twirling the tail end at his shoulder so that he pivots away from you. If he refuses to budge, you can use the end of the rope, or you can stick your hand up to his eye and flick your hand so to speak to get him to move away from it. If he moves forward, immediately back him, then try again. If he steps sideways, then forwards, reward him and allow him to walk on.
If you can get that, then you can practice doing the same thing on a longer rope.
Once he understands that his shoulders are to move out before forwards, you're on your way to teaching him how to lounge.
Remember that your energy should always be directed towards his shoulders and/or entire front end, but not as his hind end. Sending him from his back end will send his hind quarters away from you, which makes him turn and face you. So always send him from his front end.
If he stops and turns into you, be quick to walk into him and push his front end back out onto the circle.
Let me know if that makes sense, or if you need more information. :)