Here's the cast list from 2002's Participation:

AjO - Spike
AngelRachel - Willow
Aurora - Horned Demon and David Fury (Man who got his shirt dry cleaned)
Prince of Lunacy - Xander
Dirty Socks - Buffy
elusio - Dawn
GreenLion - Saved Man
Pooka - Sweet
Kiba Rika - Anya
Leila - Marti Noxon (Woman who gets a ticket)
Little Willow - Tara
Slayed Soul - Giles

Vampires were played by:
Destiny
Lazy Girl
Lilyana
Princess of Darkness

The Ensemble was played by:
biobabe
hostile17
Jeanie the Tortoise Fly
Mally B
The Host
Y_slaybelle

Look at photos!