Hi 
I faced the task to calculate the Axis parameter of RotateAround for an arbitrary transform so that none of transform.position coordinates is 0 but the Point of RotateAround vector remains (0,0,0)
May be somebody knows the answer?
Humm… I may have misunderstood your question, but you could perform the RotateAround for your arbitrary gameObject, and then use the transform.LookAt( Vector3(0,0,0) ).