EPS as Background Image?

Hello,

I have a simple question, that I am having trouble finding a simple answer for: Can an EPS file be used as a background image in a PostScript program?

Here is some background (no pun intended):  I have a standard Letter sized .jpg image that I have converted to an .eps file.  (I've tried using both GIMP and Image-Magick for this).  I then try to call in the eps into my postscript program, expecting it to act as a background image, allowing my variable data to print over the top of the .eps file.  This is not happening.  Instead, the .eps file covers up all my data.

I've tried changing the order of when I call in the .eps file, but that doesn't seem to make a difference here.  I've also looked briefly at clipping limits, but even if it did work, it does not apply since the .eps uses different shades of gray, all of which need to be over-printed.  Creating the graphics on the fly in regular PostScript is not an option either, as the graphics are too complex for that.

I'm pretty new to PostScript, and everything up until now has been "learn-as-you-go", so I'm hoping that I've missed something simple, and this is an easy fix.  I can provide samples if need be.  Thanks in advance.

Matt