Swing out from the platform. At the backend, bring the legs up in front and hook your toes onto the bar with flexed feet. Just before the peak at the front end, let go of your hands and hang down from your feet for a split second before making the catch.
You can find out more about this trick in my books:
IMAGE CREDIT: 1st: Diana. 2nd: Thanks to Emerald City Trapeze Arts. Flyer is Lynn Cafferty Treadwell. Thanks to David Treadwell for the photo.