You need to measure camber with the wheels sitting on the ground - so attaching that to the hub is out. Could it be attached to the brake disk through an alloy? Depends on the wheel, I suppose. :-/
I would save your money and use a spirit level with a spacer at each end to sit on the wheel rim, top and bottom. Make the top spacer a little longer to give the desired camber.
Purely from memory, about 7 or 8 mm extra at the top of the wheel will give the desired 1o10 'ish of camber when the spirit level is showing vertical.
Hmm. Perhaps I should take some photos as I'm not sure the above made sense. :-/
Kevin
EDIT: Of course, once you've adjusted the camber the toe will be out, and that's less easy to rectify accurately on a DIY basis.
On reflection, I agree Kev.
When I set-up the camber on my previous car, that's how I did it.
After slackening the two bolts, I managed to wedge a cold chisel between the leg/hub carrier, (with the car 'on all fours'), and tapped the chisel downwards until the desired setting was achieved.
Rechecked after a short run, and all was well. Tyres wore quite evenly, and car ran in a straight line.

Obviously, a bit fiddly with the wheel in-situ, but do-able nonetheless!