Can I make epiphany use other than gnome default pdf viewer?

I would like to be able to use another pdf-viewer than the default gnome pdf-viewer that the epiphany web browser comes set up with. I did a standard debian 3.1r1 install, which gave me epiphany 1.4.8 Is it possible to configure epiphany to change its pdf-viewer? I can't figure this out from the

gnome shutdown no longer asks for root password

When I initially got my gnome desktop up and running (default debian 3.1r1 install), I was glad to see that it would not let you shut the system down without asking for root's password. Something has happened since then - I have no idea what - that causes the shutdown sequence to start of immediat