Ok.

I made a fast and dirty conforming third eye for La Femme.

What I did step by step was 

Extract one of LF eyeballs and regroup it internal name 3rdEye.

Moved it into position on her forehead and then created a "socket" morph in LF's head to house the new eyeball

I also painted a socket texture over her existing one in Mudbox/photoshop and blended it with her base texture...

Next, with the new eyeball selected I entered the set up room and loaded the LF dev rig and chose the head hierarchy (just the head, neck, chest, waist, and hip actor hierarchy) to add to the new figure. I then added a new bone for the new eye as a child of the head, I positioned the bone as you would for a typical eye rig. In this case I didn't need to revisit the rig in the joint editor because I was very careful aligning the new bone and the rotations turned out fine.

I named the new bone matching internal name as the new group existing in the eye extraction (3rdEye). 

I then exited the set up room and saved my new figure to the library. Started a fresh scene, loaded a new LF, applied the socket morph, loaded the 3rdEye figure and conformed it...

All of this took about 45 minutes.

Obviously the results would be much better if I had used HD morphs and spent a little more time with it. If I had spent a week on it it would get pretty outrageously elaborate. This stuff is easy. I just explained how to do it.