OK, I'm just dredging up a bunch of old topics here, as I chew my way through every ounce of information I can find on this site. What a great resource; Thank you all.
I wanted a sort of semi-standardized way to use store bought cheese to replace powdered cultures, cuz they're expensive, and hard to get locally, and powder's kinda a hassle to deal with (measuring, rehydrating, avoiding clumps, etc.). Really, it's not standardized at all, but it's sensible, repeatable, and, more importantly, seems to work.
Here's my method. I take 2oz of store-bought camembert (or my own, assuming it turns out, which it seems to be doing), and 6oz of filtered, boiled, cooled water (store-bought distilled would probably be easier, but whatever). Then I sterilize a pot, an ice cube tray, a fork, a strainer, and some tongs, and bring another pot of filtered water to the boil.
Then I use the sterile tongs to grab the hunk of cheese, and dunk it in the boiling water for ~2 seconds. I don't know how necessary or effective this is, but I remember it from some old advice about how to make steak or tuna tartare at home -- pasteurize the outer layer, as the interior of a piece of raw muscle will be sterile. My idea was that the candida or roqueforti will have colonized the interior of the cheese, outcompeting anything else, so killing off any pathogens which might've made their way to the surface of the cheese would be a good safe plan.
After that, just dunk the cheese into the cooled water, mash it with the fork (probably give it a few minutes to get soft) until most of the bits are dissolved, and pour it through the strainer into the ice cube tray. you should get about 8 disgustingly off-white cubes of inoculum. Pack 'em in a bag and label. I used 2 cubes of p. candida in a one-gallon make, but I imagine one would do fine. Your guess is as good as mine when it comes to how long they'll stay potent in the freezer, but I'd say... longer than expected, but not as long as powdered. They're hearty little creatures, anyway.