The good news is: IT WORKS!!

The bad news is: it doesn't work for everybody. I tried it on Egelric and Leofric first, and it didn't do anything. Then I tried it on some of my most recently created characters -- Saeward, Enna of Leinster, and still-hot-out-of-the-oven Robert Curthose -- and it worked GREAT.

So now I have to figure out what's up. I read that this mod assigns the body hair color based on the Sim's hair color, so maybe there is a problem with Egelric and Leof wearing a custom, non-color-binned hair? I think my other three test subjects are all wearing binned hair. I will also look at their genetics and see if there's a difference. In the worst case (like maybe the Sims are just too damned old) I can always clone their looks onto new Sims with SimPE.

Yay!!!