Hey Bsquared,
In the Brewing industry there are set standards of what pitch counts should be for ale and lager brews... well that is in the books you can read at least. In the industry its done by weight harvested and is what works for the brewery.. often more around .75x10^6 cells/ml per Degree Plato. I looked at three different pitch rates for Brettanomyces during my research. Biochemically the organism acts differently then Saccharomyces cer. so it can't be thought of in the same way, well not exactly. While a higher pith count on Sacch species could mean off flavors and a lower pitch count the same or a beer which doesn't finish, with Brettanmyces it's different as there is no standard fermentation. What flavors are you looking for and what pitchrate is going to get you those flavors? Also in homebrewing it can often be good to pitch 1.5 times the "standard" pitchrate as the yeast are at a different acclimation point due to mechanisms of fermentation used (fermenter size, shape, head pressure, ect...)
To get to answering your question I would recommend 2x10^6 cells/ml per degree Plato, or even slightly higher. The higher the cell count the more flavors which were produced and the better the fermentation profile. I assume your looking for the Brett flavors so a higher pitch rate appears to achieve these slightly better.
As for propagating, grow the Bretta up in a 1.048 of 12 Plato starter for at least a week to get your cells growing and built up to a level which allows them to sustain activity for the length of fermentation you require..
Final word of advice, use a different Brettanomyces strains also. Why just one? I would recommend B. lambicus from Wyeast... as a good Brett strain too. I have some strains I could send you if your interested which are not commercially available.
Chad