Here it goes...
(I will have a pic after each explanation, and then at the bottom of this all I will have the link posted to the fixed mirrors.)
As you can see, this was not just a fat mirror face, but also has some of the mirrors frame attached, and is also tagged with the mirror material... This will cause a problem cause now it is trying to render the mirror on the entire thing.

Next I detach both mirrors faces, so I now have two separate polys, 1 with left and right mirror faces, and one with left and right mirror frames.


I then set the mirror frame with a new material (carbon Fiber) and called the material mirror_surround.


Now I just do a basic flatten unwrap of the frame.

As you can see the mirrors were NOT unwrapped, they were basically 2 flat lines.

Now I do a basic "Front to Back" unwrap, Set the bitmap size to 1024x256, set the template bitmap to the mirror.bmp, use the "Free Form" Gizmo and scale them something like I have or to your liking.

Now you should see something like this....

Write your GMT's......

And now in SimEd (I only have the old version) Looks like so....

And that is all there is too it....
http://www.realracin.net/Mirror_Help.7z