Page frames/watermarks

[Psalle]

Hello all,

I was wondering how to add a decorative frame to a score within 
lilypond, which led me to search too for absolute-positioned images in 
the way of a watermark, but found nothing relevant. I'm aware of 
\epsfile but in my experience it works inline.

Is there some advanced trickery to achieve this? Thanks in advance for 
any pointers.