For fun, I asked about this here on pprune years ago. In amongst the very entertaining discussion, there was a link to a personal web site of an ex skipper who'd practiced the loop on his home PC and then apparently flown it to perfection in the sim after a check ride. It was a great read - ISTR he needed 20k do it top to bottom!
Anyone know if the story still exists?
Or better still, tell us about really doing it.