I would first ask the user if the main tile is set at the chincompa spawn or not; If yes, then i would check for short bow and enough ammo. Would not mess up with the attack style so as to not gain defence xp. Then, the bot should just mark that one chincompa which spawns on the main tile. If the chin goes 2 more tiles(radially) away from the main tile, you hit it with an arrow to kill it thus making it spawn on main tile again. This increases the chances that he will get caught in one of the boxes around it.
It can take this further by asking user is there is another spawn within say 5 or 6 tile radius of the main tile. If yes, i can kill that chin too for a chance that he will come to box trap quicker. But this step is unnecessary work.