Copy the "textures" folder to Fallout New Vegas/Data
Copy the "GreenScreen" file to Fallout New Vegas/Data
When not using, Remove the textures file


I was lazy, 
SO if you want to play without the greenscreen effecting anything else,
I might make a new if people like it

Here is the link for all the info:
http://www.youtube.com/watch?v=5mBlDoaW8E8

If you want the best croma-ing use Keylight (in after effects)