It's not that hard to learn. It's hard to learn it in the autox environment because you're only going out for 60 seconds at a time with a limited number of runs. But I taught myself to do it on the street over a winter several years ago, and the next spring I started doing it on course.

As someone mentioned, you have to overcome your left-foot's tendency to slam to the floor. You have to learn to modulate the brake with your left foot. That's pretty easy to practice on the street as you're coasting up to a stop light and that sort of thing. From there, you can start practicing actually USING it to slow for turns (when there's no traffic around, of course) and power out of them. The first time you get it right, you WILL know.

Then you're ready to put it to use on course and get past the final hurdle... learning to move your left foot from the clutch to the brake and back as naturally as your right foot moves from gas to brake. You'll likely find yourself blowing through a turn or two from pushing on the clutch trying to stop... or locking up your brakes when going for that 2nd gear downshift. Eventually you'll get it right.