The fact that you're a hunter rider should not make much of a difference. In this case it's all about taking the horse back to the basics in order for it to feel comfortable with what you're asking it to do and not try to evade that by running off. Start off on the lunge line some days. Get him used to side reins, and if you use them a few times a week that should help you strengthen his top line. In general eventers are under-muscled and hare excess stamina, so this should kill two birds with one stone. I'm not totally clear by what you mean when you say "he hates dressage". My mare hates dressage too, and she just finds other ways to entertain herself, rearing, bucking, spooking. So for right now I'll assume you mean that your horse thinks dressage is boring. Cool. I do too. I take it that a big portion of your problem lies in transitions down from canter to trot. There's opne exercise in particular that I like to use in that case.
Start out on a 20 meter circle at the trot. Slowly leg-yield in to a ten meter circle. Don't ride a diagonal in, the legs need to be crossing over. Once on a ten meter circle, slowly leg yield back out, making sure that the legs are crossing over. As you go back out and your horse is relaxed, ask for the canter. With a horse that tends to run, you probably don't need to sit in order to ask for the canter. The correct time to cue for the canter when you're posting to the trot is when you are up in the air. Play with canter cues when you sit and when you ask on the up beat of your post to see what works. Once you're in the canter, canter a few laps around the 20 meter circle. When you want to transition back down start leg-yielding to a smaller circle. Make sure to rock your horse back on its haunches and not pull him into a smaller circle, it all has to come from the inside hind leg stepping under more. While leg yielding in to the middle ask for the trot. Voila! One Canter-Trot transition.
I have a few more exercises for canter-trot transitions, tell me if you want them. For an event horse the problem is often that their energy is being blown out the front end, rather than them actually using their hind end to thrust underneath of them. Leg yields in general are a great exercise to get them to engage their rear end. This all assumes that your horse will respond to lateral cues, if not, start teaching leg yields, here's a good website for that:
Leg Yield
For jumping I do a lot of grid work with a rushing horse. You can shorten the distances when he gets a little more advanced to really make him sit up and wait to a fence. I do a lot of jumping out of the trot too, as this keeps everything a little calmer. Another great thing to work on are skinny fences. They require a lot of accuracy from the rider, and horses are apt to have run-outs or stops at them. Jumps on a circle are another thing that will help you contain all of this horse's energy, as you can't run around really fast on a circle, instead you have to focus on turning.
I hope that helped, if you have more specific problems there are probably more specific exercises, but that should give you some ideas on things to do.
