This lift is named after strongman Henry "Milo" Steinborn who performed all his squats this way. Think of this lift as a Turkish get-up for the truly strong.
To rack a bar in the style of the great Steinborn, first upend the loaded bar so that it rests on one end. From there, position yourself in such a way that you can tip the bar onto your back, typically into a deep squat position. Then stand up with it.
Once standing upright, you can squat as normal. Dropping the bar at the conclusion of the set would be ungentlemanly, so replace the bar the way you picked it up, by tipping it down on one end first, standing it upright, and then gently lowering it down to the ground.
A word to the wise: A bar with center knurling will remove flesh and leave its mark, making it clear you've been doing some unconventional lifting. And if your gym floor isn't soft rubber that will hold the bar end safely in position, have a partner use his foot to block the bar end.