It sounds like you'll be in tight quarters and if the subject is moving you'll need a light source that's able to follow with them about the space. Given that, shooting a Leiko or any light into the ceiling may not be your best option, especially if you want to keep the source contained close to the subject.
What you could try to do is go fishing:
Get a 6" china lantern with an appropriate Watt tungsten globe (I'm guessing 60w and below but that will depend on what your recording platform is). Next, double-up 2 C-stand arms and affix the China lantern to one end. You can have an electrician hold the lantern off camera and get it as close as he can without the lantern being in frame while another operates a dimmer that's connected in-line at the hubble if you don't have a Magic Gadget or flicker box. You can also use duvetyne to cover up portions of the China lantern to make it more precise.
This will allow your source to be contained closer to your subject and also simulate a more realistic and appealing candlelight/lantern effect.
I know you were trying to obtain a dancing effect like that of an actual flame. However short of using an actual controlled fire source to light the subject there's not much that can give you that specific effect that I can think of. If anyone else knows of something that does, by all means, chime in.