I also couldn't find the short connection points during my first transit though IST, but I was able to find them today. It is a bit counterintuitive as the short connection points are at the end of each international pier (i.e. away from the main terminal hall). There are some signs as you get out of the aircraft. The short connection point is essentially a mini transfer security. Not sure though what exactly they will do after the screening - put you on a buggy and drive you to your next gate?