Swing out from the platform, get one leg up and pass it between your hands, holding it straight in an almost-Split position. At the backend, hook the front leg onto the bar and simultaneously drive your head and shoulders between the trapeze cables, making a full front roll around the bar. You'll end up in a Gazelle position. Catch a Gazelle at the frontend as usual.
You can find out more about this trick in my books:
Thanks to Rachel, Brenna, Marine and Toan for providing a video for this page.