Start in the dead-hang pull-up position. Instead of pulling straight up, pull to your left side, touching the top of your left pectoral to the bar. Descend under control, then do the same thing to the right.
You can also go side-to-side for two reps before descending: pull to the left, hold at the top, transition to the right, then lower yourself. Start the next rep by pulling to your right.
There's nothing more frustrating than committing to a training program that doesn't pan out. This is equally true for an athlete who might work hard yet still falls short of his expectations and the strength coach whose biggest satisfaction comes from the great strides his athletes make.