reguardless of how fast the car is going, its not about that..... its the way his hands move around the wheel to get the car to do/go what/where he wants. a fluid motion, moving hand position all the time, crossing of arms, etc.
race corner speeds are higher and your obviously not trying to get the backend to step out. but when it does step out i agree it all happens very quickly.
the fastest way to get opposite lock on is simply to let go of the wheel and let it center itself, but catch the wheel before it corrects the slide, to avoid fishtailing dont immediatley correct the slide hold the backend out and keep your foot down. i sure you know that already!

while ive not "raced" on a circuit ive done many trackdays in company lotus elises/exiges, my stripped out audi 80 sport and mk2 golf gti. at croft, cadwell, snetterton, malloy + oulton park. i also took my national b last year at croft, tho ive not used it as plans fell thru.