How do I use print to generate a PDF of all entities referencing a specific node?
Seeing the url for print layout works fine, my first suggestion would be, that you can actually do it simply by activating the pdf module and changing the path to trigger the 'pdf-generator':

print-path:
http://fanbards.net/print/stories/13008

printpdf-path: http://fanbards.net/printpdf/stories/13008

…you may find further useful info about this on the documentation page for Print.