Sometime useful for better positioning, but mostly to show off.
1° Move your body slightly off-centered, towards the fall by twisting the waist.
2° Carry on turning on the front wheel, with the back wheel well lifted in the air.
3° In one hop on the front wheel, eject yourself from the wall and carry on the twist.
While pivoting on the front wheel, to 90°, keep the rear wheel well above the horizontal, until you have decided to push-up on the front wheel to carry on the twist. Else, with the rear wheel too low, the front wheel tends to stick to the edge and you 're up for a crash on your back. See this move in a video
In the air, pull the bars towards your chest to stabilise the bike in front of you. Let the back wheel hit the ground first, with the rear brake "on" to gain extra damping power with the "bottom bracket-to-rear-hub" lever. Use the spring of your legs to absorb most of the impact, then lowering naturally the font wheel to the ground by extending the arms. Here again, fat low pressure tyres are more comfortable.