In one of his seminar videos on mmajacked a long time ago he showed how he escapes from open guard.
It looked very simple but thats prob because he was doing it and not me lol but here is what he dose.
First he gets a underhook with his left arm then he twists his torso to the right as that shifts his opponent to the side he sits up gets his right hand behind his back and uses it to scoot or just stand up.
He does have a few videos you can find on Google but I cant seem to find the specific one Im talking about, He did say that this was the most effective way he's found to get out of bottom position.
"I fear no man, but Jim Harrison and Mike Stone are the two last men that I would wish to meet in an alley fight. Jim Harrison's fighting style is not flamboyant or spectacular, it's just simple and deadly!" - Bruce Lee sakurabushidokan.homestead.com