The key is to think backwards.  

In real life, of course, the brain gives signals to the muscles 
which move the pickaxe.

In Poser life, think of the pickaxe as the intelligent element,
which knows how to perform its particular moves.

Move it through the proper cycle, then take both hands 
(with IK on) and parent them to the pickaxe, so that the tool 
is the parent and the hands are the children.

(Maybe this isn't -quite- backwards after all...  when you get
accustomed to using a tool, it feels like the tool is in charge 
of the movement, and the brain is just sort of monitoring.)

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