Quote - You need a glass which is uvmapped to position the letters

Then it is a matter of adding a mask

This is the simplest way of doing it. Now you can modify the glass as you wish

See example

Math node is a simple substract to get the inverse 
Fresnel is the standard default fresnel
The texture node contains the movement of the lettering to get it into position

 

Did that ;). But thanks. :)

Laurie