Heed submitted a great walkthrough of how custom content should be installed and deployed in NWN2.
There are several ways to get custom content into the game, but not all are equal. Some have advantages over others and some can actually break your game install making you unable to patch your game. This document will describe various methods and highlight best practices.
Head over to the Vault and give it a read:
http://nwvault.ign.com/View.php?view=NWN2Tutorials.Detail&id=56%3Cbr%3E