PS7: Recoloring images

I generally know how to colorize images, but there's one certain effect I'm trying to do. I'm trying to color hair white, and everything I try ends up grey.


Effect I want:


Original:


Does anyone have any clue how I can re-color the hair white?

[credit for 'original' goes to this website, and the example credit goes to Sniktbezerker of wolverine&rogue]