I can't seem to be able to use the portal in Irenicus' dungeon. It keeps asking for some key I can't find anywhere? Is there something I'm missing, or has the install been ineffective?

Which portal? The one to level 2 or the one that starts NeJ? The one to level the second level is in the bedroom beyond the Dryads. The portal that starts NeJ should not need one.

The one that starts NeJ.. the one directly north of the starting point, right?

I really don't think you should need a key for that portal, make sure your party is close to it when you try to use it.

Just to confirm what Chev said. To start NEJ you don't need a key. Just take every one in your party to the room and active the portal