So Ziva now ships with it's own rivet tool.
To use it, select one CV on your curve, and then add the bone geometry to your selection. (The bone geo must already be a Ziva bone)
Select Ziva > Rivet to Bone
computePolysetVolume is a built in Maya command, you have a spelling error in your text: computePolysetVolue
Let me know if you have trouble!