Here is something you can try:
You need to desensitize your horses legs first, then sensitize them to pickup the foot up on a que that works for you.
First, start with a dressage whip, or something that extends your arm, start on the front legs and rub them up, down, inside, and outside till the horse ignores it. Better to start high and work down towards the feet. If the horse picks up the leg as you are rubbing it keep rubbing until the leg comes back on the ground. For the rear legs face the rear put your one hand on the rear of the horse which will give you and indication of what the horse is going to do with his foot and standing at arms length away do the desensitizing process. When this is going good take a piece of rope eight feet long or so (couple of meters) and sling it around the lower legs, pasterns, etc till the horse ignores that. When this is going good run your hands down the legs till the horse is fine with that.
Sensitizing to lift the foot: Front foot, loop the rope around the back of the pastern and apply light pressure until the foot comes off the ground, immediately release. Do this a few times then hold it up for a few seconds, ease it down don't drop it. You are looking for the horse to stand on the other three feet and hold the foot up in a relaxed fashion. For the rear feet you may want to loop your rope on the ground and have the horse step in the loop then gather the rope up and behind the pastern for the first time you try to lift the rear foot. Put light steady pressure on the back of the pastern and when the foot just starts to lift let the pressure off. Repeat as with the front feet until horse is comfortable lifting and holding feet up.
Using you hands to lift feet:
Some people squeeze the tendon in the back of the leg just above the pastern and the horse treats the irritation as a fly and lifts his leg. I have taught my horses to pick up their feet with a light tap of the hoof pick on the side of their leg above the pastern.
Once your horse will lift the foot off the ground and it is relaxed you can position the foot for whatever you need to do.