I have one of Sharen Thrawn's design docs for M478 from August 2008, if that's of interest. It's labelled as version 2.1. There don't appear to be any Selkath, and, despite a note about how I was going to format my comments, I don't appear to have commented on it.
I last worked on that mod c.2009, as I recall. The issues with it were to do with getting the hoods to match the robes in a regular manner (the texture looked different - and hence, would match the robe more or less closely in almost every area), clipping issues at the back, and the near impossibility of compatibility with robe mods. I still have the files somewhere, but modding is not a priority in my life right now.
For reference, here's what I have on the subject, from my probably-never-to-be-finished module editing tutorial. This was probably written in 2008, and may well be wrong.
MoonFogColor – Sets the colour of the fog at night.
MoonFogFar – MoonFogFar and MoonFogNear set the amount of fog in the area at night, if you turn fog on. NB: These two settings work in different ways. MoonFogFar sets fog emanating from the edges of the area (or the room the player’s in?). The higher the setting, the further away the fog starts out; the lower the setting, the nearer the fog.
MoonFogNear - MoonFogNear sets the amount of fog emanating from near or around the player. This is really good for making a really foggy area, but it can easily make everything in the area totally invisible.
MoonFogOn – Turns on/off (by setting to 1 or 0) fog at night; without this turned on, MoonFogFar/MoonFogNear will not take effect.
The other thing I've noticed is that, as far as I can tell, fog has no effect in the Steam version of the game. My guess is that if this is the case, it was disabled by Aspyr on the basis that fog is no longer needed from a performance perspective. If I'm right, though, it's annoying if you wanted to use it for ambience.