Swing out from the platform, bring your legs up at the front end, pass them under the bar and hold them straight in front of your face in a whip position. At the backend, push your straight legs over the top of the bar and follow with your body. Let go of the bar and grab the trapeze cables. Pull yourself quickly into a sitting position. At the front end, jump off forwards with a full twist (straight body) to catch.
You can find out more about this trick in my books: