He probably won't eat adult mice because he knows you'll give in and give him the fuzzies. I would try to offer larger meals (hoppers) every two weeks for a while and then move up to small mice, then large mice. If you feel that he'll still refuse the mice because of his past what about weanling rats? They have a completely different smell than mice and he might go for it. Also, have you tried various methods of f/t? Thawing at room temp, in hot water, feeding out of the cage as well as in? As weird as it sounds I have a baby burm that refuses to eat outside of his cage and I'm going to have to slowly wean him off of that, but he will eat. I would try offering bigger food and if he doesn't eat he doesn't eat. Don't give in because he's learned that he'll always get what he wants. A healthy adult corn should be able to go a few months if need be without food. One of my males went 4 months last spring without eating and only lost around 50g. Keep in mind that if the vet says he's healthy he probably is and you shouldn't have to change your feeding schedule - it's just not one that most people on here would recommend. I'd second Lenny on checking with the herpetologist on corn experience and whatnot. Whatever you end up doing, do it for the benefit of your snake, not because you feel pushed to do it the "right" way.
~Katie