Thanks, everyone! It was a really big step. Before, he pretty much could not look at a boarder without freaking out. I was feeding him jerky non-stop. Yesterday, he could look at them from a sitting position, but even when he stood up, his tail stayed level with his back, so he looked more watchful (maybe even curious???) than threatened.
Of course he started off today by peeing on a rug in my apartment for the first time in months.
It's a long climb up the mountain, grasshopper.