Ehhh...I still firmly hold that horizontal wall runs accomplish nothing without a slanted/curved wall to assist them. I practiced them for a little while until I realized that a regular tic-tac is a far more efficient and versatile technique.
That said, if you approach a 2-step wall run from an angle starting with your outside foot, you can get a boost in height while traveling laterally. This, however, is not the same as the multi-step Prince-of-Persia style HWRs you see people attempt to do in videos and such. The first step just pushes you up the wall a little before you kick away from it. Remember to point your knee.