I don't use the book module in Lightroom, so I'm just going to have to say that I don't think you can do what you want to do. There are a number of styles provided in the book module, and as far as I know, those are your choices.
I use other sources to do my books, and I use the software provided by the company to create the book. So I'm probably not the best one to provide help to you. But since I misunderstood your initial question and obviously made a fool of myself with my answer, I thought I would reply. Someone else may have a better answer for you.