I’m always looking around for the best in how-to info and this is indeed one of the best, from www.paddlesurf.net. It tells the story of the cutback in a way that makes sense and seems doable. 
Not that I can do it. But if ever I’m able, it’ll be because of these instructions. Bueno! It starts thusly:
At a request from Anonymous: “hey ho: could you offer up a little how-to tutorial on your pole-plant snap pivot? when i try it, i always end up flat on my ass in the water, but when i’ve seen it done correctly, it looks great. but … i just can’t figure it out. care to weigh in?”
Alright Anonymous, I’ll do my best.
To do this turn you should be able to wrap a standard, non-paddle assisted cutback. I’ll explain why this is important later but for now, if you can’t get your board into a cutback on legs, torso and shoulder power alone, you should take a time-out and work that out.
Photo: The end of a snap-pivot turn. Notice that the paddle is to the inside of the turn? This comes from planting the blade and arcing away from it. Once the blade’s reached the inside of the curve, the weight transfer can happen which frees the fins up for a big slash.
The snap pivot relies initially on an arcing turn (that’s why you’ve got to be able to turn your board!) and ends with the use of the paddle. In the final part of the turn, the blade becomes both a pivot point (as it pulls your inside rail around) and as weight supporting, planing surface as you unweight and blow out the tail. If you push hard enough, the turn looks like a snap and the board ends up pointing back towards the breaking wave. It’s a fun, cool turn that throws a nice little fan and feels good when you hit it just right.
I like to use this turn on the shoulder of a wave so that I can build up speed and throw it all into a lateral redirection. A more difficult variation (and I’m still working this one out) is a snap-pivot that’s thrown up into the lip as your jamming down the line. To be honest- the guys that are throwing this variation of the turn are the true rippers. Throwing that much board up into the lip, blowing out the tail while leaning on the paddle takes a ridiculous amount of timing and skill- something to work towards. However, I digress, let’s talk about the steps involved in this maneuver.
You’ll be planting your paddle into the face of the wave so be sure that as you go down the line you’ve got the blade oriented to the inside, wave face side, of your body. As you approach the shoulder of the wave, reach forward as if you were going to take a stroke and plant the blade into the water. At this level of the game, don’t pull on the paddle as you execute the turn- as your skill level increases, you can begin to crank on the paddle into the turn and generate a tighter arc and a deeper gouge. For right now, however, just plant the blade, transfer your weight to your heels, look over your shoulder to where you want your turn to go and begin your standard cutback.
As you turn, you’re actually turning away from and around your paddle. The trick to this move is to leave the paddle in the water. As you arc around, the paddle will transfer from the outside of the semi-circle you’re scribing in the face of the wave to the inside of your turn. As the paddle reaches the inside of the turn you can lay back onto it. You will feel your weight transfer back onto your paddle allowing you to push laterally against the fins overpowering them and sliding/snapping the tail around. The feeling is exactly like power sliding a skateboard- you’ve got to commit to the weight transfer to free up the fins in the slide.
Here’s a tip: Wait on the snap. The snap portion of the turn comes at the very end- as you come around you’ll feel like you’ve completed the cutback- and you may begin to think you’ve missed out on your opportunity to throw a hack. Be patient, remember the paddle must transfer from outside (wave face side), to the inside, keep laying back and waiting for the weight transfer. The weight shift comes much later than you’d think but when it does- HAMMER DOWN ON IT! Throw a huge fan, redirect and glide away.
One last thing- before you can incorporate your paddle into the action you’ve got to be able to pull off a fairly decent non-paddle assisted cutback. If you can’t get your board turning, you won’t be able to wrap your board around enough to bring the paddle to the inside of your turn- and you’ll end up bogged down with your paddle hung up in the face of the wave. Practice, practice, practice!
Stand Up Paddle Surfing: How To: Pole-plant snap pivot… what?