G4 CPU replacement "How To"?

I want to upgrade my dual 1.25GHz G4 MDD PowerMac to use the dual 1.42GHz G4 FireWire 800 CPU card. It is my understanding that the bus speed for both of these models is the same and the swap should be an easy remove and replace procedure, but I can't find any information that describes exactly what I am trying to do, or how to do it.

I also would like to possibly over-clock the dual 1.42GHz G4's up to 1.5GHz, or 1.67GHz, if they do not produce too much extra heat at those speeds, so information on where to find directions on how to over-clock the dual 1.42GHz G4's to 1.5GHz, or 1.67GHz would also be welcome, in addition to opinions on the reliability and stability of this modification.

Thanks,

David