You need to take the car to an airfield where you can lose control of the car at high speed and gain confidence in your ability to (a) see it coming, (b) respond to it.
Trackdays are part of the solution of course, as are fast-ish road runs - the more you drive it, the more natural everything will seem.
I have the same problem in high speed corners - I'll happily push the car to the very edge in slower speed stuff, knowing that I'll most likely sort it out should there be less grip than I had hoped for - but in high speed corners, I cannot (easily) persuade myself to push the car to its limits as I just don't have the confidence that I'll catch it should it all go wrong. For my next walshy day I was planning on concentrating on higher speed cornering, losing control and learning to fix it.
Of course for hillclimbing you don't actually want to be driving like that, but unless you have the confidence to sort it out, you won't push it I think! (I'm assuming good times are achieved by committed but smooth driving, with only a small amount of brute force required).
Talking of pushing it, I was very impressed with what I saw of Alonso's driving this weekend - he was pushing that car very hard and losing it/recovering it in some really tricky situations when he pushed too hard. He deserved to do better and it was a shame that his car let him down (albeit after a bit of a donkey punch on the first corner). I wish I could drive like that (too fat to actually get in one, though
!
Cheers,
Robin
P.S. there is the odd track where you can try some of this safely - e.g. the first big corner at Anglesey will generally let you away with it, but the trackday organisers probably get pissed off with you after a while, eh Neil?
However not so sure about Doune, my "Imagination" was definitely working 
