I would like to use Add Attribute feature to create new attributes to my setup and use Set Driven Key to control them. Before I start, I will do some clean up works.
1. Select pelvis joint and go to Window -> General Editor -> Channel Control.
Highlight the channel that you don't want to be key, click Move >> to make them non-keyable.
2. Go to Modify-> Add Attribute to bring up its window.
I named the attribute name to Jaw, Data Type set to
Float, Minimum=0, Maximum=10, Default=0. Then O.K.
3. Now we have got Jaw's attribute in Channel Box. New attribute has been added to pelvis joint.
I will use Set Driven Key to connect Jaw's attribute.