Trying to Bootcamp a macbook with the LCD not working

I'm trying to bootcamp a friend's laptop, but the LCD is broken on it. He's been using an external monitor while using OSX.

The issue I'm running into is when Windows begins it's start up routine, it doesn't use (or register) the external.

I'm not surprised by this, however I am stumped on a possible work-around.

Anybody have any suggestions?