Well, Mira has had about 4 "training sessions" (if you can call them that, less than 5 minutes each!) and she is still doing well with learning the trick. I had an absolutely insane week last week, so after that first time, it was a couple days before I even tried a refresher with her. I was feeding her, and before I put the bucket down, I decided to see if she remembered. So I gently tapped the back of her cannon bone with my foot, and before I could even say the "Foot-foot-foot" cue she had picked her leg up! She was very quick and looked at me like, "OK, I did it, now I WANT MY FOOD!" LOL
I was tickled pink that she remembered. :-)
We've done a couple more quickies like that, just to keep it somewhat fresh, and then today I got a banana and we did a short practice session again. This time I also introduced the concept of moving her leg towards a tap on the front of her cannon bone. I will continue shaping the trick until I can "draw" her leg in any direction I ask. And then eventually, I intend to refine until I can just point at the leg and she will pick her foot up.
To Photogchic, I'm afraid I haven't tried clicker training with her, so I can't really tell you which is the best way to go, but Mira seems to have picked this way up quickly. Too quickly, maybe - it might not keep your Maddy occupied for that long! Although, I bet she would enjoy showing off for the farrier! :-)