Well, if you wouldn't mind terribly taking a very slow turn around an empty parking lot with a big tape measure and some chalk along while you still got em? The roll center is very difficult to calculate from the geometry (it's somewhat force dependent) and very easy to get from measuring the turning radius. Also, I assume you're running like a bananas amount of negative camber?
EDIT: you probably don't care much about your car's scrub radius. Let me try another way:
Yo dude! Welcome to the forums! I like white cars too!
2015 STi: Still Stock
04 STi, 04 WRX: SOLD