You may want to consider using Ghostscript directly, which can read both postscript and PDF files, but can also output them as well. You can also limit which pages you want to output, thus effectively 'deleting' pages from the PDF. With ghostscript, then, you can distiall the ps to PDF and thus get back your original file. You can call ghostscript directly from perl, if you need it in such a format. Ghostscript is free and available for most common platforms.

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Dr. Michael K. Neylon - mneylon-pm@masemware.com || "You've left the lens cap of your mind on again, Pinky" - The Brain
"I can see my house from here!"
It's not what you know, but knowing how to find it if you don't know that's important