This is a great exercise to build your deadlift and teach you to maintain proper position when squatting. Because of the position of the barbell, it forces the lifter to maintain tight abs, an arched lower back, and proper chest position.
Begin by placing a bar in a power rack just below your armpits and unrack it in the crook of your elbows. Keeping your back arched, stomach pushed out and chest up, squat back until your thighs are parallel to the ground. Make sure to keep your elbows and arms close to your body. A shoulder-width stance is usually used.
Stand up by thrusting forward with the hips.
The amount of weight you can hold in your elbows will limit the bar weight used on this exercise. Some of the pain can be alleviated by placing a single 2 x 6 board (approximately 16-18" in length) in the crook of your elbows and placing the bar on it.