loading of embedded OS on die (boolean logic silicon gated transistors)

I am affiliated with a company that has been studying possible backdoor technologies embedded in some CPU. We believe that the backdoor system is made of a special backdoor CPU and an embedded backdoor OS. The question is simply how probable is that we could somehow code the right instruction(s) to command the backdoor CPU to load embedded OS which is stored on die by way of boolean logic silicon gated transistors and not ROM and not EEPROM and not flash memory ? We know absolutely nothing of the likely custom instruction set of the backdoor CPU.