Catch normally and at the apron end, bring your feet up to the catcher's arms. Rest the top of your feet on their biceps and push your butt through into a Bird's Nest position. As you swing back, the catcher will twist you so that you are facing the right way to take your bar.
You can find out more about this trick in my books:
Thanks to Hull and Fly'n Fit Trapeze School in Japan for providing a video for this page.