You might want to try some exercises like the movements used in Grooming and Showmanship classes. These movements involve leading the horse at the walk and trot, halting and squaring up his feet, backing up, and pivoting around the hindquarters. The idea is to get the movements so natural that the horse can do them off of the handler's body language alone, with refinement through the lead.
The G&S movements accomplish much the same as NH lunging: you're moving the horse's feet on your terms, making the right thing easy and the wrong thing hard, and reinforcing the concept of respecting your space, particularly through the pivots and backing up.
Hope that is helpful to you, and I'm interested to see what others recommend!