I tried to explain it well... its the ramp directly behind the teleporter that connects to the deck behind the building. While facing that said ramp, the glitch happens on the left of the ramp. You must be crouched down and aiming your gun in the direction of the teleporter.
side note: to activate the superman glitch while under this building, try to glitch your way to the far left corner and stand up. roll into it if you have to. your character will sometimes shoot into the air.