1. Start pumping like you normally would for a pumping session (same settings).
2. Pump for about 15 minutes.
3. Turn your pump off and take a break for 5 minutes.
4. Turn your pump on and pump for 10 minutes.
5. repeat steps 3 and 4 until it been 1 hour since you started pumping.
I personally like to do this watching a favorite one hour tv show, it makes the time past faster. And to eliminate watching the clock, I pump the first 15 minutes and then use commercial breaks as my time to turn off the pump.
You'll want to use your power pumping session in place of a normal pumping session. I'd recommend doing this once a day for a week and you should notice an increase in your milk supply. I've had many moms tell me they think they get better results in the morning if they do their power pump in the evening or as the last pump before bed - no scientific reasoning for the timing but hey it's worth a shot!