For example I see that CAM:PDF has a function to ADD a page, but it does not look like it can be used to INSERT a page (at the start of the document).

:) That's funny, cause insert is 1) start new pdf 2) copy insert page 3) copy rest of pages

http://search.cpan.org/dist/CAM-PDF/MANIFEST stamppdf.pl, appendpdf.pl,