Well after calculation all the various resistor values I needed, the non-Trinket parts are on order from DigiKey. I've added a link to my BOM (its public if you have an account on their website), right next to the OSHPark and Dirtypcbs links. For now its off to writing the software side as much as I can without the hardware. That will mostly be setting up the structure, analog reads, output mechanism (I have one of those Nokia LCDs in the drawer I might use for this), and guessing at the algorithm with fake data.