Since it's a position I use myself, and I know how scattered and sparse tutorials are for it (or used to be, before Eddie put out his book), I thought I would compile all the rubber guard techniques I've found online in one place.
I must warn you though, even with all of these online tutorials, I didn't really start to get rubber guard until someone with experience in it personally showed me it and had me drill a couple moves. Maybe you'll have better luck. I really just recommend finding someone with experience who has been working on the rubber guard for a while and having them teach you.
Let's start with Eddie Bravo's site, TheTwister.tv:
Invisible Collar (arm/shoulder crank): http://thetwister.tv/Technique01.htm
Meat Hook (triangle setup): http://thetwister.tv/Technique03.htm
Invisible collar again:
You can catch some rubber guard action in his anti-gi propoganda movie:
GrappleArts.com has two:
Meat Hook again: http://www.grapplearts.com/Rubber-Guard-Setup-1.htm
The New School (triangle setup for MMA): http://www.grapplearts.com/Rubber-Guard-Setup-2.htm
Lockflow.com has a triangle setup by Eddie:
BJJFighter.com has footage of the Meat Hook to triangle being used in competition:
Sherdog's User Submitted Techniques has a rubber guard guillotine (I think Eddie Bravo personally posted his approval at some point):
And lastly, NOT KEMPO: