I have to write a "virtual printer driver" for OSX, to ensure that once the user presses Command+P to spread out paper dialog, he sees my virtual printer...which is accustomed to generate files of numerous types, rather than physically printing to paper.

I am a new comer to the topic, I looked around a little but found nothing. Have you got any link or mention of the documentation which cover this subject?

Instead of writing a person, think about using the PDF Services feature of OS X print dialogs. Either in the machine-wide /Library/PDF Services or perhaps a user's ~/Library/PDF Services directory, you are able to put AppleScripts, Automator workflows, or symlinks/aliases to programs or folders. Individuals products can look within the PDF pop-up menu within the print dialog, and when the consumer chooses the product, a PDF from the file is going to be put into the folder or perhaps be passed towards the application, script, or workflow.