Sorry I don't know of a book reference but I've shot the New Model Army more than any other percussion revolver design going back to the 70's. Most of the time all I do is remove the cylinder (and the nipples from the cylinder), remove the grips, remove the trigger guard, flush everything out with nylon toothbrush and soapy water, flush with clean water, then dry on a baking sheet in the oven at 250 degrees for about 15-20 minutes. While the parts are still warm, I relubricate everything (including the lock), towel off the excess lube and reassemble.
People have different methods and so long as you achieve the goal of removing the fouling residue and protecting the metal afterward, you're going to be good. The NMA design is one of the easiest to work with but as I mention, there's no need to disassemble the lock work for cleaning.
