Have you seen a coining press? There's a couple at a museum in Carson City. Pretty impressively massive machines.
Discovery and/or History Channel have done shows covering the US mint's coin making. If you can get copies of the shows, that'd give a good overall view, though at the high end of production!
Not sure if it's still there, but Nevada City had a small mint up to a few years ago. Google on "Nevada City Mint", there's some links that suggest he's still operating now and then. Perhaps one of the links will get you the owner's contact info, and he might be willing to help you track down some info.
How hard can it be, if the ancients did it. Of course they weren't forming cupro-nickel. But a 40 ton shop press should develop plenty of force to get many metals to the yield point, at least on a small die. Gold, silver, zinc (pennies) would be easy. Steel or stainless might require heating and a quick strike to get good flow. Just my guess.
Say, I happen to have a box of 300 1-inch 321 stainless slugs on my for- sale page:
We taught ourselves using trial and error, I'd love to learn more. We produced commemorative coins for first one friend's 50th anniverasy of getting his pilot's license, then for 3 retiring radiologists from a local hospital.
History Channel had a great epsiode on "Breaking Vegas" where this guy was making casino chips for slots. He perfected the dies using an EDM while his friend a toolmaker ran the punch press for the blanks. He had to fine tune the alloy also. Since chips aren't legal currency , there were no laws stopping him in Rhode Island. When he stepped into NJ & NV is where he ran into trouble.
My impression is that the mint guys (or secret service?) are pretty confident that they'll nail anyone trying to produce counterfeit coins though the supply chain, rather than by trying to conceal the methods of making coins. If sheets of cupro-nickle go into your basement, and cupro-nickle doo-dads don't come out...