Basically it was a table with the left hand columns being the instructions to perform, in point form, and the definitions of the expected/correct behavior, and the right hand columns being checkboxes and blank spaces to write in, indicating whether the software performed correctly.
It was super clear and to the point, and it was just a document that could be easily updated (and was, I believe I later made some modifications to the script when new versions of the software came out, but it was so long ago that maybe someone else was the one to do it).
Maybe you could write one of those up and he'd get a better idea for what his job was, and you could run through it with him a few times. After he gets the hang of it, I think it will have some value outside of just testing the code: he may come to understand how changes in one part of the code bring up issues in unexpected places (and get an intuitive grasp for, say, code reuse); he will be a true expert on the product (I've always noticed that QA people are often better versed in software than the assigned Product Manager, come demo time); and perhaps he'll start to grasp at a more physical level what your work actually entails, and it'll help give him context for software development as a process.
"The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds his castles in the air, from air, creating by exertion of the imagination. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures....
Yet the program construct, unlike the poet's words, is real in the sense that it moves and works, producing visible outputs separate from the construct itself. […] The magic of myth and legend has come true in our time. One types the correct incantation on a keyboard, and a display screen comes to life, showing things that never were nor could be." - Fred Brooks
Let him learn some of the magic behind the poetry :) To your whole idea (biz/product guy getting hands dirty with product work), hear hear, bravo, etc.