I wrote these alchemy rules for what is rapidly becoming the "never-to-be-finished" Necrocarcerus Rules version 3.0. Someone asked for a list of alchemy ingredients, and I realised I already had one written up, so I scraped the rules and the lists from that document and have uploaded it to Google Drive as a handsome PDF. As always, most of it is a series of bad in-jokes and allusions for which I apologise pre-emptively.
These rules represent a distillation and refinement of the procedures in Procedural Metapharmacology and Alchemy: The Junkie's Science, and can be supplemented with the procedures outlined in those posts as well as in my post Determining Magical Item Components (all of which are actually just more prolix variations on the advice "Use your random encounter table to determine what the PCs need"). Enjoy!