the best thing to do to avoid copyright would be to buy a current Hellboy comic, remove the staples and cover then replace it with the new cover. I will upload PDFs of my stuff as soon as I have a spare minute.
The actual back cover of the comic can be seen clearly in the scene where Myers looks at Hellbiy for the first time then back down to the comic. It is a custom one created by dark horse comics I would think, based on one that originally appeared on the back cover of issue three of a dark horse comic book called The Amazing Adventures of the Escapist. On that one though the prizes shown feature Hellboy collectables yet on the movie one it has been altered to show other none Hellboy related things.