In order program the distance in your mind, take a look at the hole (or breaking point) and then back at the spot. Now, using the correct stroke length for that distance, roll the ball over the spot that's six inches away. If you read the break correctly, you should come very close to the hole or even nail the putt!
Dave says not to look at the ball when you putt, but rather to pick a spot a couple of inches in front of the ball, right on the putting line you have chosen. Then when you make your stroke, simply focus on rolling the ball right over that spot.