How to unscrew freewheel sprockets with 9 broken spokes A friend of mine has this problem. I haven't seen the wheel, but I suppose that the broken spokes are in one "area". It's a 27 inch wheel.

Is there any tool that can hold hub tight enough to use a freewheel wrench?
This one is way easy. Use a pneumatic impact wrench.  There is very little torque transmitted. Bruuupppp and its off. I use this a lot with my single speed spin on cassette with the torque from Hades. When I did this manually, I needed a six foot breaker with wheel tied down. Impact hammer is awesome. 



No vise. No marks on part. I would just hold hub carefully with work gloves.  Heck, bring it by my house, we'll have it off in 30 seconds.