I can't get close. If you really want to train for this I'd start doing them on a gravitron witrh as much assistance as you need to do sets of 5-8 to condition the arm, then drop the assistance to where you canonly do 3-5 per set. Keep dropping resistance whenever you can do a set of 5. Eventually you should be able to get one without any assistance. You'll also know how much work you have ahead of you the first time you try it. Personally, I wouldn't bother training for this unless we're talking decent $$$ or I'm already close to doing one anyway.