Stand with shoulders under padded bar.
Elevate shoulders as high as possible. Lower and repeat.
If possible, position lever height high enough so weight will not need to be squat up that high, but not so high that weight stack bottoms out during exercise. Since this movement becomes more difficult as full shoulder elevation is achieved, height criteria for shoulder elevation may be needed. For example, raising shoulders until slope of shoulders becomes horizontal may be considered adequate depending upon individual body structure and range of motion with lighter weight. Also see ROM Criteria.