I believe if you make the moveto location close enough and right behind then the NPC will just back up. You could make a sequence of really short moves. Look at GetBehindLocation. The default will almost certainly be too far. But you can copy the code and use smaller distances. This is just a guess though (i.e. I have not tested this). You can simulate it, of course, with a PC and the mouse without wasd. Just click close behind.
