We both got to visit the Bartons drying plant during the last Sampler. And yes, BT has their own drying plant as well, I saw it during a "backlot" tour that same week.
In the old days it was common for a distillery to have cattle and pigs right on the grounds to make use of the slop. I imagine they dry it these days to make it easier to transport to the farmers. (And it keeps a bit better)
I guess a food processor might do it. I seem to remember that the Kitchenaid mixers have a grain mill attachment available. Or if you know anyone who makes their own beer they could mill it.
If you are able to score some spent grain from Greg, please grab me a reasonable sized bag and I'll gladly reimburse you for your effort!