1. set up your suspension (camber atleast) the way you want.
2. measure in mm from the point you want to be flush to the point where you want to be flush on.
3. buy spacers + longer studs or studded spacers.
4. install. done!
http://www.pandagarage.com/Interior/wheel%20spacer.htm
*edit* you might need more than 25mm :/