I have used a tool from "Stein Co." which clamps your Campy fixed cup wrench to the BB cup, not allowing it to slip off. I have used it 100's of times and been able to secure cups to the correct torque specifications. I have used both the Campy tool and the VAR in shops where I use to work and yes they are Great but at a price. I paid 35 bucks for my Stein Co. cup some 15years ago. For the buck, its my favorite.
And on a side note, it is pretty easy to over torque BB cups with the VAR and Campy tool. Especially when you are utlizing vices and other methods. Calibrate those arms ...... have heard of people bending frames that way (okay that was Columbus EL :-)).
Los Altos, CA, USA