From what I understand you cant. You need the shoulder belts to be at a 90 degree (45 degree? anybody know for sure) angle to the floor, so you really need to connect them to the back seat bolts. Otherwise the belts wont work properly. My friend has those same belts installed in his mustang and there is a second belt release behind the headrest so that when he needs to carry rear passengers he can just undo it and thne use his stock seatbelts. Hope that helps.
