If you're in a capsizing-prone position, you should be at the very least hiked out. In this position you'll end up sitting on top of the windward rail.

If you're pushing the boat that hard you should be trapezing anyhow. In this case you'll be trying everything you can to keep the boat from capsizing, but when the moment arrives, do a little 180 degree hop and grab ahold of the rail. Hang from it for a second before dropping into the water. If that's a little to gymnastic for you, just try to bend over and grab the rail as you fall.
Capsizes generally occur slowly enough to give lots of reaction time.

Pitchpoles don't.
You're only hope here is that you're sitting on the boat when it occurs and can grab ahold of something to keep yourself in place. If you can keep your weight on the back corner of the boat, there is a fair chance that it can swing into the wind and settle back onto both hulls. I've seen it done all of twice, everyone else just got catapulted.