Nope! I have never done it either.
Been riding some twelve years and never needed to do it.
Having said that yes I would like to do it and I know how to do it. Toes on the pegs, one cheek on the seat, stick your knee out and most importantly look down the side of the screen and look where you want to go, its easy.
But I have still never done it.
Like Bikerbladeash I am also in the IAM and did some track training at Mallory and had the same instructor as Ash, a police rider (racer) known as Woody, he's advice is supurb, having the right leathers improves your chances of getting your knee down, if they are too tight they can restrict your leg movement.
What a lot of riders don't realise is that they already have the bike at the correct lean angle it's just that they need to change the position of their body a little and theyv'e done it.
I will have to admit that Bikerbladeash was quicker than me on the day, but I put that down to the fact that I am older and wiser.
If you are trying to learn something knew make sure you have a more experienced rider with you who knows the dangers involved in what you are doing, Keep it safe!
There is nothing wrong with learning something as long as it is done safely. (meaning you and everyone else around you)
Oh by the way Ash and myself are not old gits who ride BMW's