Safari extension question

My company recently released an extension for IE and a FireFox (also
Windows) version is in beta right now. I am very interested in
releasing this tool for Safari as well, and while I have done some Mac
development before, I haven't touched Safari extensions, and after a
cursory investigation, was wondering about the Safari's UI.

The product (Printer Friendly : http://www.antair.com) currenly places
an additional button on the toolbar of the IE and FireFox browser.
Safari doesn't seem to follow such UI rules, and from what I read, a
plugin can only be activated by HTML tag content for the currently
displayed page. In order to release Printer Friendly for Safari, I'll
need to put in a way for a user to indicate that the current page
should be printed - whether a button (on a toolbar?) or a menu item.

What are the rules of the land for Safari concerning this? Are there
resources which demonstrate Safari UI extension of this sort?

- Cheers
- Andrey Butov
- Antair (http://www.antair.com)