well, as nfries88 already said, you can realize it's with setting monsters speed to 0 and teleport them by 1 tile with pushmove = true, probably a addEvent rotation... But if you want do this for normal monsters, I guess it will be hard even from sources, cuz monster will pick target and move to target all the time, instead of going to waypoint
edit.@Syntax, right xD Forgot about it