Here's one page with some E-6 formulas:

http://opie.net/orphy/photo/dr/wkft-e6.html

Note that there's no reversal bath; the procedure calls for exposure to light instead. Also, I've not used these formulas; I've just bookmarked it for future reference.

On another note, I hadn't heard about Velvia 50 being discontinued. Is that in all formats or just some? Although I don't use all that much of it, if 35mm Velvia 50 is going the way of the dodo, I'll have to stock up...