No need to pitch Brett at lager pitching rates - you should treat it like sacch when using it in primary fermentation. It will easily attenuate better than sacch.
When I said you need Lacto/Pedio to get sourness, I was referring to a sour level you would get from commercial examples. Yes, Brett can produce acetic acid. The amount is still very tiny compared to what most people seek in a "sour" beer.
You need Pedio or Lacto to make it sour. With Brett, all you will get is the funk.
Check out http://www.brettanomycesproject.com/dissertation/ for more information.
Bryan,
I have had great results using Hannsens dregs as well in a few beers.
As for the JP dregs, I believe their beers have Brett, Lacto, and Pedio. Crack open a bottle of their Perseguidor 5 or Lambicus Dexterius and you will agree.