Ensure the pulley is at the lowest point on the cable machine, this may have to be adjusted after you set up.
Sit down with your feet towards the pulley and attach the cable to your ankles.
Lie down and elevate your legs with your knees bent to a 90 degree angle.
The pulley should now be aligned with your knees.
With your hands at a 45 degree angle on the floor, bring your knees in towards your torso, keeping your hips on the floor.
Pause for a second, then in a slow and controlled manner, bring your legs back to the starting 90 degree position.
You should still have tension on your abs in the resting position, continue on for the remainder of the set.