We did a couple this past weekend at a local ski show.
Most of the time, people do this on skis, but it is possible to do it on a wakeboard.
If the rider is regular, start out going straight at 25-28mph.
Step 1. Make a steady right turn to whip the rider on their heelside edge. This should get the rider going at her/his max possible speed. I usually give the boat some extra gas when making this first turn.
Once the rider is at max speed, cut the wheel as hard as you can to the left, let the rider pass in front of the boat, then straighten out once the rider is behind the boat again. You will have to find out what works best for your boat. Some boats will not make the turn without letting off the gas. Some boats want a more rounded left turn, as opposed to what I described above. Try it a couple of times first without the rider to see how your boat turns around the fastest and keeps the most momentum.
During this whole time there is a good chance the rope will get slack in it. The rider should try to keep as much tension on the rope as possible while trying to stay afloat as long as possible. When you first start out, you will more than likely yank the rider. Keep working at it to try to get the rope tight through the entire turn.
I should mention that this is dangerous. Be careful. Use a long line at first (75'). I have seen people shorten the rope to make it more impressive (and less slack gets in the line), but I don't do it that way.
Drain all of the weight from your boat. Use a tower or a pole. Remove boardracks or anything the rope can get caught on. Use common sense.
Another thing that helped us when we learned this was to practice whips. Have the boat turn to the right as before, but when the rider gets at max speed, let them let go of the rope and drift as far as they can before sinking. You can also drift into a triple up to make it more fun.
If you have any questions, let me know.