EDIT: Here's my attempt at following the steps. I'm proud of the results even though I couldn't get the same effect with the circles (might be because I'm using CS4)

Also I've noticed a couple things...
- The purple things are the bit between the brake lights (I changed them to grey in the above picture)
- Anything done to the front lights won't be visible to anyone using low settings (the low version doesn't use glass)
Finally I see your point on the front lights. I think the main issue is that the actual size is considerably larger than the actual space given in the DetailsDiffuse.dds. here's a case in point