I've discovered multiple options for convert a few to serveral PDFs into Postscript, but many are command-line programs with command-line limitations (this application lives on .NET).

Our application generates tens-of-thousands of PDFs that we need to send to a printer, except BEFORE the Postscript is printed we need to edit the Postscript to insert print command instructions (duplex, tray-pulls, highlight color, etc.)

I think a perfect solution might allow us to write the PDFs to a stream, and simultaneously allow us to read the output stream so we may edit the Postscript before writing it to a file.

Of course, if I must create the file first containing all 10,000 PDFs and edit it in an additional pass, I'm OK with that, too.

I should mention that speed is important. I need to print 10,000 at a time, but need to keep the printers busy 24-hours/day.