Well i don't know if it still works or not so can't answer that, but how it works is by comparing the string '[GM]' with the players name that just entered your area (the function is only called when a player enters your area) then if the name does contain '[GM]' it does whatever it meant to do. Now player detect script, works the same except instead of checking for any names, it just moves them into a buffer and you use CE to display what's at those offsets.
You can combine player detect and GM detect, the easiest way of doing this is just adding the check for '[GM]' into your player detect script.