I'd suggest going to the GTAC website and using your Webkey account, login and go to Documentation -> NX3 and read ALL of the plotting guides on the website. There should be 3 of them: NX 3.0 Plotting FAQs, NX 3.0 Plotting Quick User's Guide and NX 3.0 Printing and Plotting.
If those are of no help, GTAC would be your best bet IMO, unless someone else with that experience decides to reply.
Here's what I did for our HP Laserjet 5000N, which uses PostScript to output a .ps file (which I then convert to PDF with Ghostscript/Ghostview freeware):
1. Start NX and open Print Admin.
2. Once you get to the Print Master-Print Admin dialog, click on the Models tab.
3. Select the SDI PS

S model and save it as a new model. I then select that new model name and edit the Properties to what I want (paper sizes, quality, etc.)
4. Once I have the model finished, I click on the Printers tab and add the Printer by Paper Size (i.e. 8.5x11 postscript, 11x17 postscript). Be sure to specify the proper Initialization file and get your System Profile set the way you want.
5. Save everything and exit Print Admin. Open a part file and select the Plot icon.
6. I have preset my output to use Custom 3 Widths to control the line weights. You can play with those numbers and save them if you wish. When ready, click the Plot button to bring up the NX Print dialog.
7. Select the Printer/Output format pulldown and choose the Printer; under Output Options, select Print to File.
8. Make sure everything else is set the way you want (centering, scaling, etc.) then click the Print button.
9. NX will prompt for the save location for the .ps file, so map that out and name it accordingly....if you have a Distiller type function with watched folders for CutePDF, dump the .ps file there.
There is a method of using Render File then Execute to automatically create the PDF, but I am not familiar with that method.
Hope this helps.
Tim Flater
Senior Designer
Enkei America, Inc.