This rare arrangement is used when the flyer is performing a trick that involves them passing backwards between the fly cables. The lines are passed between the fly cables before starting so they do not tangle.
ATTACHING: As you face forwards on the platform, hold the safety lines in front of the fly bar. Pass them backwards over the bar and between the fly cables, then bring them under the bar and connect them to your belt as per Regular Lines. Make sure that, when you hold the bar, your arms are in between the lines.
TRICK EXAMPLES: Pullover followed by a Back Hip Circle
You can find out more about this trick in my books: