From my experience, there is very little clearance in the bezel threads to fit a thin Surefire rubber gasket, the thinnest lens I could find (I mean online, not just in my spares box), and the Xeno rings. The ring wouldn't even make contact with the threads!
I have a newer model I believe though; another member (houtex I believe) managed to do it, but he mentioned once that his one came with a two piece bezel/lens assembly instead of a single unit like mine.
I too have been trying to find a solution to this problem because my bezel is denting up like mad from drops. Hopefully someone with a solution will present themselves!
I have an idea that just came to mind to use the extremely thin O ring that comes with the G2X with the thin lens and try to see if that fits. I'll try it sometime soon.