Attach a climbing rope to a high beam or cross member. Below it, ensure that the smith machine bar is locked in place with the safeties and cannot move. Alternatively, a secure box could also be utilized.
Stand on the bar, using the rope to balance yourself. This will be your starting position.
Keeping your body straight, lean back and lower your body by slowly going hand over hand with the rope. Continue until you are perpendicular to the ground.
Keeping your body straight, reverse the motion, going hand over hand back to the starting position.