Oh. I thought you meant as an ADDITIONAL display. Sounds like you just want to configure a headless mac. That should be possible without any hardware just using Screen Sharing. Google around for instructions.
IIRC, you should be able to SSH into a virgin Mac and enable screen sharing on the new Mac. You might need to monitor your Airport (or other router) to see what IP address it hands your nMP on bootup, or you could use internet sharing from your rMBP (Share Airport to TB-Ethernet port, and plug ethernet into nMP).
I think plugging in a wired mouse and keyboard to the headless nMP might be even easier/faster for you (this apparently will allow Screen Sharing, which should cause the nMP to appear in Finder on your MBP under SHARED).