How can I make a certain bone rotate with the camera?

I am making a first person game that uses the full body and I want to rotate it realistically, so how do I rotate the Spine with the camera? Actually, scratch that. How can I rotate 4 bones with each bone moving 1/4 the speed of the camera? That way it looks a little more realistic with the full body turning. Thank you!

var vecttoq : Quaternion;
var parent : Transform;
function Start(){ var parentRotInv : Quaternion= Quaternion.Inverse(parent.rotation);
vecttoq = parentRotInvtransform.rotation;
function Update(){

assign the parent as the main/parent object at parent. attach this script to the spine or whichever part you wish to rotate with camera

if the objects are the children of the the bones as u said, there movement should be proportional to the bones, however if they are up in the hierarchy they will move according to the main gameObject.