We do lots of finger conditioning from grabbing steel shot bags and tiger claw push ups. It's also good to strengthen your wrists also. In Gung Gee the part where you do the three Tiger Claws you rip down and pinch your fingers together in a fist. All seizing and grabbing techniques.
My sifu has demonstrated the pinch on me many times and yes I whimpered like a girlie man. The underside of the arm, sides of your stomach and lower ribs area hurt especially. It does help to have a rock hard body I suppose.