i have been told (and seen demonstrated) by Audreannga that teh glow powders available on E Bay are GREAT!
try these:
http://cgi.ebay.com/GLOW-in-the-dark-POWDER-4-gel-Candles-nail-art-GBA_W0QQitemZ12028308942 9QQcmdZViewItem?hash=item120283089429&_trksid=p3286.m14.l1318
not sure about how to mix them, but i'm looking forward to buying some and experimenting!
(ty Audrey for this hint!)