*sigh* Don't you love igornamuses? Yes, some of those high flying front legs with no hind leg to speak of are rather artificial, but certainly I have never heard of using similar methods to the TWH's to gain this movement. It is more through tension than anything else.
Dressage horses seem to be being bred now for this big, high stepping action. Watch them out in the paddock or on the lunge with no contraptions. Lots will get excited and have their knees around their ears in trot and canter! Under saddle, work them correctly, with a soft back and in collection, and the movement will naturally become higher and shorter as more weight is taken through the hind quarters. The forward motion becomes replaced with upward motion.