If you bought all 6 cyberlimbs could they move about on thier own, being rigged? Or there rules for humanoid drones I missed somewhere? How durable would this be? I don't really know where to start with one of this. One of my players is wanting to build a humanoid drone.

A few Anthroform drones coming in arsenal. Rigger in a box full borgs in augmentation. Unless mean hacking a samuri with all six body replacements or he's allowing you control?

Another quick thought as far as rigging Just the cybernetics, wouldnt be possible...torso and skull are just shells as per bbb not solid cybernetic components.

Power supply?

If possible at all, it would require a minimum of of Move-By-Wires or Skillwires in order to do so, and you'd have to constantly do battle with their own conscious control of their body while attempting it. Cyberlimbs have little to do with such a concept since they are, in fact, cybernetic instead of robotic. Big difference between the two.

You could probably try knocking them unconscious or otherwise disabling their conscious control, but doing so could compromise the attempt due to just how much of their own brain keeps the basic body working properly.