Have you checked to see if there's any heat on his front hooves? Has he ever had any lameness or founder issues?
My one gelding was almost impossible to pick up his front feet. It was always a hassle. But when he would finally pick up his feet it wouldn't be for long.
When we moved him and my other horse back in June, i started to pick up his feet and reward him (with either a treat or a rub) anytime he tried (at first, shifting weight, then picking it up a little bit, etc etc until I was able to pick it up and hold it there for a while.)
On his one leg, that has caused him the most pain (he has arthritis), i would take the end of the hook pick and press into his leg. I'm not sure on the exact location. I can point it out, but not describe it (but I will look it up in a second). It made it uncomfortable and he would lift his hoof. After just a few sessions of doing it, I can now pick it up fine.
This will take a lot of time and patience, but if you're determined, and the horse is healthy and sound there shouldn't be a problem.