I figured out a way to get Harley to ONLY walk.
Take the saddle and longeline completely out of the equation.
To accomplish such a task, I went out to the pasture holding the bridle and my helmet. I bridled him in the pasture, walked him over to the mounting block, clipped my helmet, and crawled on him.
We walked for 40 minutes. Some around the pasture, but a lot of focused walking in the arena. I thought going over the trot-distance (4'6") poles at walk would be easy. HAH. Not even close. He stumbled, fumbled, tripped, even stepped ON them a few times.
When he finally cleared the poles in both directions, I checked my watch. Yeah, that's 40 minutes, and a good place to stop. I took the bridle off, and proceeded to the pasture gate. Harley followed. :)
So I put on his halter, walked him to the wash rack, and hosed him off. too bad I couldn't have done the same to me. My jeans were wet, YUCK!