There's a really nice book that came up in a thread a couple of years ago called 'Numismatic Forgeries' that goes into detail on these processes.
It's good for us because it tells you how to go about making your own coins, if you're so inclined. Well, not 'coins' so much as 'tokens'.
One of the things on my list of 'stuff I need to get around to doing' is to make a little hammer struck coin press and a pair of dies. I'm thinking of one that folds over and clamps enough to hold things in place so it's easy to whack with a small sledge.
That web site is run by Robert Kokotailo, a very knowledgeable man in ancient coin circles. Steve, the hinged dies most likely were used for lead seals, not coins. I've tried that method and all it takes is one off center hammer strike and your die alignment is shot. The hammer striking jig in "Numismatic Forgery" works great, I made one 4 years ago and have used it at the ANA summer seminars for the last two years with dozens of students smacking it. Attached is my newest coin striking jig. Its a number 10 screw press, about 2,000 pounds of medieval coin striking fun!