Drive shaft hub nuts.

[voucht]

I used a pretty long piece of 25x25 tube, leftover from the chassis construction.
I drilled 12mm holes across it.
I put one of the wheel studs in the hole.
The tube was long enough to touch the floor and being blocked by the stud and the centre part of the hub, it stopped the wheel from spinning while I tightened the nut with the torque wrench.

It worked fine, and I did not damage the stud's tread. However, protecting the tread as Arfon wisely says can't hurt of course.

I used this technique more than once, and actually I always kept this tube which is still lying with my tools

2013-11-21_18-39-14 by Sylvain ROIG, sur Flickr