I recently did some work to capture dancers lit by stage lights in a dark theatre and came away with some ideas.
Some things to consider.
You will need to gather as much light as you can by using wide aperture to mitigate slow shutter speeds. I find that anything less than 1/100 second is too slow when dealing with subjects that move. You would do well to set your camera to fix at that speed and let it figure out ISO and aperture.
Also, practice panning, as you will want to follow the dancers as they move. The dynamics will be apparent in the resulting image with a moving scene where the dancers are somewhat frozen in motion.
Since these dancers will be on swinging ropes and such, there will be moments when the movement is minimized, at the top of an arc for example. Anticipate these moments as the subject will be still. Know your shutter lag and be prepared to press the button before the critical moment.
Lastly, find a way to brace your camera to still allow controlled movement. A monopod would be ideal as it will give you the flexibility you'll need.
Hopefully this will help!