Snowman: display a specific passage in all passages?

I want to implement something like Harlowe's footer/header feature... specifically for a menu for inventory, character notes etc. And be able to hide it on some passages (probably based on passage tags)

I'm pretty comfortable with javascript but not JQuery.

Can I respond to all "about to show a passage" events & modify the passage before it is shown? I guess I would do this in the story javascript? How would I go about it?