Others with more experience will weigh in--I'm replying mostly to see their comments--but from what I understand, you won't need a starter. Brett working in secondary does not need the vigorous and relatively quick start that is ideal for a sacch fermentation; Brett is happy working slowly on long-chain dextrins over a period of many months.
Please correct me if I'm wrong! I've never worked with Brett.
I had a big belgian that completed fermenting with good attenuation numbers but still tasted a bit sweet to me. On a whim I opened 2 bottles of Orval and gently poured all but the last inch in the bottle into glasses, then pitched the last inch from both into the 5 gallon secondary (a corny keg for me). It worked beautifully to dry out the beer a bit and added a little brett funk... nothing overpowering.
Come to think of it, I have a Saison coming out of primary today and some Orvals on the shelf- I might split the batch (5&5) and pitch Orval in one for a comparison.
I thought i'd pass this along http://www.solarhomebrew.com/East_Coast_Yeast.html
this guy loves bugs!
he grows some interesting yeasts- I haven't used his bretts yet (still drinking Orval instead) but have used the Newark Ale and Saison Brasserie with good results. Made in limited quantities, you have to get on the mailing list and order it within minutes when they are available before they sell out.