This was first discovered by Veyron, and I borrowed the idea lock, stock, and barrel for the article that covered the build of this Celica in Scale Auto.
If you have an airbrush and Alclad Chrome, it's pretty easy. You have to do everything backwards, and apply the black mask/surround on the glass first. Then mask the window areas you don't want to paint, then very lightly apply the Alclad inside the glass..it goes in microscopically. A gradation is pretty easy. Then you seal it w/some smoke tint on top of the chrome. It's pretty easy. Remove masking and you should be done. From inside the car you can see out.
Here's an example. It looks better in person than in these pics.
