I never stretch a horse, it is not allowed, but I would think the method is the same wherever the feet end up!! Just stand in front and give your command (I say "Stand square") and then "jiggle" until they do it- it will take a while. Once they attain the pose you want for a moment reward and move them off the spot them start again. Eventually, with the correct rewards, the horse will stand as long as you wish. I would not even attempt to get the ears up and the neck out until the feet are rooted to the spot!! It can be fun!!! I love it when I have cracked it and whilst others appear to be attempting a round of WWF wrestling with their horses I just say "Stand Square" and get what I want!! This started in the dog show ring and I figured if a dog could learn it so could a horse!!
This one is actually pretty easy to teach with the clicker. Condition your horse to the clicker, and then start teaching the horse to "Stand!". It helps if you also stand perfectly still. Stand him up how you want him, and command "Stand!" (or whatever). At first, try and use your best judgement, and just click and reward BEFORE the horse moves. What you want to do is gradually lengthen the time the horse will "Stand!" before you click and reward. This has the added benefit of really getting them to focus on you, so that can help in the showring. You can eventually teach them to stand still while you walk in a circle around them. However, for most horses, once you are out of sight they figure they are off the hook and can do whatever they want!
So I don't think I would walk out of sight. But they will hold still for a very long time, just waiting for that click!
Is actually quite easy. I showed Morgans for years and this is about the ideal for stretching IMO. Some horses get to like posing this way and will over do the pose. I start with a little--teach them to stand square first, then gradually move the front feet forward until they're where you want them. Then of course you want them to lean forward so that they're right up over their front feet, with their croup flattened. Nothing looks worse that stretching a horse & then having him stand there in sawhorse stance--leg at each corner, butt up in the air, back hollow. It's helpful to start out posing the horse on an incline, front end higher--the incline will encourage the horse to stand over its front feet & it kind of conditions the horse to stand correctly once you start posing him on flat ground.
You can also coax the horse to "lean" forward by baiting him--I'll ask him to rock just a little bit forward, hold it for an instant, then tell him to come, step him out of the pose & reward him. Gradually lengthen the time you ask him to hold the pose. As you ask him to lean forward over his front legs, you can encourage him to keep his feet in place by blocking his chest with your hand. With the Morgans you cannot show with "bait" at all, but our horses learned that when I posed them & put my hands up, they were to reach forward & then hold the position. I never showed with a tailer, so had no one else there to help alert the horse in the ring.
Showing Minis isn't so different. I do have to watch not to over-stretch them for Miniature classes, but I do like to show them "parked out" just slightly. To me it's just a more polished look, the difference between showing a Mini Morgan as opposed to a Mini QH!
IMO so many people have theres stretched way to far. Some of them look like they can reach the neighbors second row of corn. I always liked to see them square over their front legs rather than leaning forward like they were grabbing an apple. But my opinion is not reflected in what is bringing home the ribbons at the shows.