Sit sideways on the trapeze. Extend one leg straight and point your toes. Bend the other and lean back until the rope is on the inside of your knee. You can hold on to the trapeze or the bent leg in the beginning, but once you’re more comfortable you should be able to release both hands.
You can extend your bent leg towards a full split (this move is also called jade split).
Alternatively, you can bend your back leg, or vary hand positions.