automagp68:
But i could just simply shut interrupts off do the set and then turn them back on. Is that what you mean?
Yes. Wrapping all calls to attachInterrupt and detachInterrupt may work but it is not the actual goal. The goal is to protect all shared resources (the hardware like the EICRA and any global / static data).
Were I in your shoes I would modify the core. That code is much closer to the goal. It will be much easier to tell if you have protected what needs to be protected.