The only method I have seen for an adjustment at the top is to drill extra holes in the strut tower on the car chassis, so you would have a few different positions with which to insert the strut into the car; or a step further is a completely modifed strut tower in the car.
Regarding adjustable camber via the control arm, Gav's method is by far the smartest way I know. I went the easy option and have the adjustable control arm bush that Warren referred to. It has an Offset 19mm Hole in it which provides the movement.
It makes the ride even stiffer due the fact that it has no rubber in the mount, rather a hard plastic substance, I think it is called Delron?