I don't know if it works for everyone, but I'll tell you how I taught Jackson. Get a long(at least 10-15ft) soft cotton rope. Make a slip knot in one end and put it between the fetlock and hoof of the leg you want to work with. (If you can't raise the foot to put it thru the rope stretch it out and put it on the ground if front of the foot. Have someone walk them over it and tighten the rope when they step in it.) Personally, when I cue Jack to give me his foot I run my hand down the back of the leg and when I hit just above the fetlock I squeeze a little and say "foot". People train their horses differently, so adapt this to however you train your horses. When the rope is just above the hoof, (best to have someone to hold them for you, rather than tied) stand out of reach of the feet and pick up the foot w/the rope while giving whatever vocal command you choose to use. As long as they fight the rope hold the foot off of the ground. When they relax let the foot down. Now, if they go tearing off and are going to hurt themselves by all means don't try to keep the leg up! It'll hurt them and probably you too. Start by only holding it up as long as they fight it and letting go, once they do well w/it you can extend the time as you go so it would be like the ferrier trimming/shoeing them. Remember, nothing is fool proof and there are a lot of times that you have to change a training method a little because it doesn't work on a particular horse. Do what works for you and your horse best.