Interesting John, have been thinking of this one in my head as well, slapping a guy in the back of the head or neck with IP strike. I learned something like this back in my ninjutsu days, but recently realized the Iron hand training makes your slaps very heavy when i slapped a mosquito on the back of my neck.
Instead of using both of your hands to push down on your opponent's back neck, if you just use one hand to push and another hand to do "willow palm" strike, even if you may not be able to knock your opponent out, you can still make him to "kiss the dirt".