My gelding has only fronts on, but he is sort of bad for the farrier. What we have to do is hold him (not put him in cross ties) and we always have either his favorite treats or about a half flake of hay available to him. When he is being good, he gets treats or hay. When he isn't we withhold the food until he settles down.
He has gotten loads better about it. He too is good for me to pick up and mess with his feet, but not the farrier. I think he knows what's going on.
Also, if you have a helper with you, the process is much easier. Someone is the treat dispenser and the other is the holder/pet-er.
I hope everything works out with you and your mare!