apart from the question WHY you would want autozenith, may be this dangerous modification could do the trick:
attach lines a little left and a little right from the center of the bar. Then attach the other ends to the side rings of your harness. Some tweeking is needed of course.
As the kite tends to go left, steering input to the right is generated, and vice versa.
Probably this results in a runaway system, but hey.