I have been looking for a solution, but have not been able to find anything. 5.6 Preview just got released, and a quick glance did reveal a new control.
An automated solution is acceptable; however, for me, I would like to have an additional control as well so that I can refine the look. Rarely is a fully automated system perfect for all cases. It may get you 80-90% of the way there, but it would be ideal to have the ability to adjsut.
The parent constrain is a good option, but under the Modular Control Rig, there is not an option to regulate the amount of rotation that is passed to the child (twist) bone from the wrist.
If anyone reads this, and finds a solution - please post it for us.
Cheer!
-=R=-