Laying a horse down changes its attitude drastically from a negative to a positive. I have a 2yo colt that wanted to react aggressively towards me any time I wanted him to move forward or do ANYTHING he didn't want to do. I laid him down with a lariat rope and a rope halter and it did take a little while to do so, he was also tired (and a bit shaky.) Anyways, I got him down, then sat on his shoulder and rubbed him about his head and shoulders, on his stomach, just basically everywhere, although I stayed near his neck until he stopped trying to get up and relaxed. It probably took a good 2 1/2 hours to put the rope on him and lay him down (I use a saddle, which I already taught him to wear), then another hour of sitting on him while he was down.
I let him up then tied him for the rest of the time it took for me to work the other horses (tacked up still.) He was the first one out and the last in. Next day, he was a completely different horse, which was awesome! He also never back slid in his training and I rode him within a week or so of that day.
I've found that that more dominant horses who have had more leniant owners are tougher to start the process of laying down, although with that being said, it has taken me probably 45days (spread out over the course of like, a year and a half) to get to the point where I can walk up to my buckskin mare, pick up her foot, and press on her chest with nothing on her and have her respond and lay down with that. Success!
Another thing I've found that really helps some immature horses grow up quickly is some long tieing sessions with a couple water breaks. When I was starting colts for people, I had 3-5 horses plus my own mare, when I'd actually ride her, at different points of training. I'd tack them all up and tie them either hard to something, or on the walker, then would start riding/working them from most advanced to the brats/untrained guys. Really helped a lot, like they had to go through their impatience and learned it did them no good, so they were ready to think and participate in our lessons =) I always ride/work/desensitize/sit on them for at least an hour each, unless there was a miracle breakthrough, then I'd immediately reward and put them up, lol.
With that being said, it is so true that you only get the brats other people don't wait to mess with, lol. I did it almost a year and quit because I was tired of it, which sucks, cause I was making triple/quarduple an hour's work at my job, which paying an awesome $7.45 an hour, LOL.
Keep going at it, Ghost, you know what you're doing ;p I bet this colt is doing sliding stops and sorting cattle at the end of your length of training. ;) Good luck!