Maybe you can adapt the code in this tip to suit your needs.
How to Silently Print PDFs using Adobe Reader and C#[
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It will probably not work if you plan to use it on a server, though, as it is using Acrobat Reader for the printing.
You could also try Redmon together with Ghostscript.
With Redmon you can create a virtual printer port, redirect the printer output to your own software, mess with it and then send it to the real printer or another software.
Ghostscript can be used to translate PDF into printer language.
This is an old article that describes just that:
PDF Writer[
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If you have problems to create a port on your computer look in the comment section for the article.
I have to admit I haven't tried this approach myself.