Hi,
What you could do is develop an external NX program (using C, C++, .NET, whatever you are comfortable with) which would print out the drawings you need as postscript (PS), using a printer that you would need to set up. You can then use GhostScript to generate a PDF from the postscript.
I've developed a very similar program, but it is launched internally (in an interactive NX session).
Marc
NX Software Developer