I don't have a write up, but I did mine and it's been holding up well for over a year now.
Edit: Here you go...same idea:
http://www.gmfullsize.com/forum/showthread.php?t=94767&highlight=painting+nnbs+grille
Edit: Here you go...same idea:
http://www.gmfullsize.com/forum/showthread.php?t=94767&highlight=painting+nnbs+grille