Okay, this is an easy one if you know what to do.
Kick the ball high enough so that you can get your first foot around the ball before it starts to come down. As soon as you're first leg is going down, start leaving the ground with your other foot. You should be in mid-air for a very brief amount of time. Good luck.
I'd suggest the first foot that goes over is your weak foot. But that's up to you.