Here's a suggestion you probably won't like.
Create a pdf version of each topic that needs a printer
friendly copy. Import them as baggage files and link each to its
topic.
You may want to "clean up" some html components in MS Word
before generating the pdf. Otherwise, the only printer-friendly
trait I can see is page breaks.
Another thought:
Some Web sites make printer-friendly html pages by taking out
the side rails, right rails, unnecessary banners and buttons,
goo-gahs, crawling text streams, flash effects and so on. They end
up with a stripped-down, plain-vanilla presentation of text and
graphics.
No need to include them in the TOC. It's not hard to exclude
them from the Index, but a bit more trouble to omit from the search
database. (See that discussion elsewhere.)
Again, I would limit this treatment to the WebHelp pages that
are most likely to need it. Unless all of your pages have left
rails, etc., etc., etc.
Harvey