Most people try to do it slowly when they get scared . This is another way of ending up with two unsatisfied, wet, customers. If needed get both of you ready and safely back on the floor, then heat it up slowly and approach the complicated manoeuvre steadily. Although less fun than just trying to "stick one in", this is more likely to provide a return for your efforts . Telling your partner to "pull like mad" can also help.
Peter Barton's training technique was simple - helm get your ar5e to to far side ASAP.
If you find you are rounding up straight after the gybe a few things that could help:
1) Let of a little kicker before the gybe (note - specific to the 97 rig on that boat, probably a bad idea on an 05 square top).
2) Get the crew to grab the new sheet on the way in off the wire. This way the kite sheet is being pulled in as they cross the boat.
3) Get the crew to sheet in like their life depends on it during the gybe, once through and you're sat down then you can blow it off again. This is slow but ensures the nose stays pointing downwind!
4) Others will be able to draw you the "S" shape you are looking to steer in the gybe. The apparent wind will really play with your head though. If possible I'd get John to helm you through a couple in your boat?
But Simon is right, swim lots and eventually you'll find the way... Did your sister get the bug?