I've updated the script uploaded in
post #11. Now it uses XMLStarlet to parse the OPF file (I believe that's more robust, and no need for dos2unix now), and I've changed the special meta@name to "prince-style". The default.css file has also been changed a bit: I moved the "@page title" style to the book-specific stylesheet, where it rather belongs, and changed my preferred fonts (grew tired of the default "st" ligatures in FreeSerif).