Tips
Using your arms can really help with this trick. Swing them wide into your cheat setup and then lift them up together with your shoulders to get more height. More height means more time for your legs to come together.
If you can already do a 540 kick, you can also work your way from there. Do a 540 Kick with a straight non kicking leg and instead of kicking over it, just connect your kick with your other leg.
Bend your knees on the landing to absorb the impact.
Try to minimize the amount of travel. You want both of your legs to land underneath you and not too far away from you.