Does your herd have a leading horse? Not a dominating bully type, but a wise, silent leader - usually it's an experienced mare who is able to control the movement, grazing and other activities of a herd by a sole gaze. Horses tend to follow the leaders naturally and as such the leaders are much better to teach others something. When I use this method, I choose a horse who is in a leading position above the one I want to show something to, for example - to teach my dominant bully the Spanish walk, I did it with the lead mare in front of him, to show something to a timid, passive horse in the lower pecking order, I did it with a calm horse who is above him, yet not too dominating and not feared, etc. These learning pairs have to be matched to work, methinks, and it is a good thought to bond such horses by taking walks with both of them in trails or just hanging around together - for example, keeping one of them in the arena while working with the other, feeding together, going on a trail ride on one and ponying the other along, etc. Of course, in order for the horses to bond better, the human involved has to be a good leader himself - basically, it is a making of a micro herd.
I have come a long way, to surrender my shadow to the shadow of my horse.