Have you tried putting your poison oak rash under hot water? It FEELS SOOOOO GOOD. It is ALMOST worth getting poison oak.....but not really.
Now when I get PO (which I do all the time mountain biking in Santa Cruz), if I put it under hot water 3 - 4 times a day it almost completely takes away the urge to itch it.
I'm talking really hot water....turn the water up and test it on a non poison oak area first. You don't want to burn yourself, but it should be almost uncomfortably hot without burning.
When you put a poison oak rash under that hot water it feels like you are scratching it like crazy (which feels awesome), without actually scratching it and cutting the skin.
This works pretty darn well for me to relieve the urge to itch.