I had kept a few of the extra black-and-white Xeroxes that I made in case there was a mistake in the coloring process, and so I scanned one of these in at the same dpi to composite into the color original. Miraculously, even though the scans were on different pieces of paper and scanned with different scanners at different times, they lined up perfectly without any digital rotation required. What followed then was a very laborious colorizing and compositing job in PhotoShop 2.5, during which I determined that the folks at Adobe must have never actually tried to color something with their software, or they would have exclaimed, "My god! Who are we fooling---this doesn’t actually work!" (Well, okay, it works, but it was written from the assumption that you simply wanted color in your picture somewhere, and didn’t really care about chroma- matching or getting a particular hue in a finite amount of time.)
Experiences like this in a retouching program remind us all that there's a lot to be said for traditional art techniques.