Internal/External Display issues

So I have an issue. My internal display on my mbp is busted. I've been using an external monitor and it works great. I know all the tricks (clamshell mode, setting the external as primary, mirror mode) and everything works great except for one thing..... I'm trying to install windows xp on a bootcamp partition. I can start up the mac on the external display and everything... but as soon as I select the windows xp install disk... it turns on the internal display (that was off and is closed) and shuts off the external display. I'm guessing the only way to get around this would be to open up the mbp and physically remove the screen... is there any other way to force it to run the windows xp install from on the external monitor?