Listen, why do you need a group of people for this ? Just read my upcoming tutorial about low light photography ;) No, just kidding, I only used a few lines on this matter, but it's interesting enough to make a whole guide on low light flashing alone. What I was thinking of is this: if your camera has a Time setting, set it to that and at f/16, or else on Bulb together with a cable release that you can lock - so you don't have to keep the shutter pressed (btw with Time you have to press again to shut the curtain, so you can leave it open without even touching it). Now, have someone else operate the camera that'll take the photo (so you'll only need one friend, or at least someone who won't steal your camera ;) and go stand in your own picture. Fire the flash (you could even use a flash on the main camera at low power, to fill in yourself, instead of using the 2nd camera's flash alone), and have your friend hold the black paper infront of the lens. Then you move to another position, take away the paper, and flash again, etc. So, you could make a photo with only yourself in it.