"Portal vs Water
CreativeGates can use either portal blocks or water blocks for portal content. You decide which to use in the "uconf".
For portal blocks to work without bugs you must open your server.properties and set allow-nether=false. This will disable the generation of the vanilla nether map and the vanilla nether portals. This is how we do it on MassiveCraft. You can add one, two or even three custom nether worlds using a world manager plugin later on.
For water blocks to work you don't need to do anything special. If you want the vanilla nether world and portals you probably want to change to water portals in the config. Otherwise players entering nether gates in the nether might exit through creative gates."
http://dev.bukkit.org/buk/bukkit-plugins/creativegates/
