Italian bottom bracket Shimano BB-6400 fixed cup tightening - what tool?
This is the tool you want, combined with any torque wrench with the proper range. 



There are a number of applications where a torque is specified by the manufacturer, but no tool fitting for a torque wrench is available.

The BBI Torque Wrench Adapter allows you to attach any "normal" wrench to a torque guage, and get an accurate measurement of the torque applied to the fitting.

I've used it with pedal and cone wrenches primarily, but it would work well with the HCW-4 on a fixed cup application.

    

Barnett's Bicycle Institute Torque Wrench Adaptor