I'd go at this a different way. Once you have him, it's time for some ground schooling for respect lessons. On a longe line, practice getting him to turn with your body language. Let's say you have him walking around you on a circle. If you step in front of his drive line, ie his shoulders, (figuratively of course, you're still in the middle of the circle) he should stop and change direction. At first you may hav to be very loud about it. If he ignores your body language, you pretty much want to run at his shoulders to he stops and turns around. Pop him with the lead if you need to. Once he gets the idea, turn him back and forth so he doesn't make a complete circle at any time. Do this exercise until he turns every time you step toward his shoulder.
Once he's back in the paddock, he's now trained for turning via body language. The fact that he's loose is not a factor. Use the same language you do with the longe line to move him back and forth. If he tries to run off to the right, head him off and send him left. He runs off left, head him off again and send him back right. Most horses give up on this game after a few minutes. He'll stop, turn in toward you and lower his head to signal his submission. Walk calmly up to him, give him a pat, and halter you horse. Hope this helps.