In my cell I've got the ambient light set to be fairly illuminative (this uses a lighting template) and this is great because the player needs to be able to see and I hate trying to work with light markers (I just find trying to adjust their scale and brightness to emulate actual light to be really difficult). My problem is I need a space in this cell to be quite dark. I haven't placed any light markers in this space and don't intend to but the ambient lighting profile whilst great for the rest of my cell, makes things far too bright in this area.

Previously I had this cell quite dark and tried to have the only sources of real illumination coming from light markers. I simply found it too difficult to have good visibility without using way too many light resources (a few red surfaces when using the Debug "# of lights" filter in Render Window Properties).

My sig links to an alpha of my mod with my original lighting setup if anyone feels like poking around themselves.
Details:

*EDIT: I would prefer to have a darker lighting template and provide illumination with light markers because those shadow lights just look too damn good.

You can separate one area with a room marker and portals and then apply a different lighting template to only that area. See the CK 'lighting' tutorial for a walkthrough.

Yeah, thanks I've got it sorted now, my cell had some pretty complex shapes so I wasn't super eager to go and roombound everything.