This question reminds me of something I used to tell people when I was doing carpentry work... You can do ANYTHING you want, (in changing a house), it is just a matter of Time & Money!
Now having said that, I too have been wanting to add some of those little lights to my mirrors. I do have some ideas. Most of them center around finding the right small lens to set into the mirror housing. Once the correct lens is found, it is just a matter of running the wiring and hooking things up. I haven't found any small lenses that will work though.