The same way you would do it with a black box while optionally taking as many shortcuts as one is comfortable with by virtue of assuming having a better understanding of it’s been built?

You can audit IntelME a similar way, it's just more annoying and tedious, it's also been done before by people. Honestly I don't bother much with the IntelME conspiracy theory much anymore (and yes I will call it a conspiracy theory, more on why later), I did used to be extremely interested in it about 2 years ago, I researched the topic heavily. I met people and colleagues who were also interested in it. However I found when I suggested ways to study or prove the claims made about it, like where it's communicating to or how it interacts with the system or even just disassembling the rom I would get weird answers about it knowing when it's being probed and that I wouldn't consider entirely rational when describing a tiny embedded system like this. Then I came across the 34C3 video and basically I realized then and there that this is a conspiracy theory, as there is a whole great study done by these guys and everyone is ignoring it.

Then there's the fact that many of the theories out there seem to resist investigation, and people seem to come up with more elaborate ways of it resisting. Example: I presented the idea of sniffing the Ethernet connection of the computer by cutting the cable in half and probing it with a debugger and they claimed that the chip would listen with the microphone and abort, or that IntelME would skew the data collected when loaded up on another computer.

The end result is that I bought a high end PC from System76 with the capability to disable IntelME largely for nothing, which would be fine if the Laptop wasn't so problematic, like the fact that it gets insanely hot and chews through battery insanely fast (seriously Battery consumption is worse on this laptop than my Steam Deck). Also it chews through power like this even on the iGPU, but it was way worse on the nvidia GPU, like way way worse. I wish I had gotten something AMD based, They're killing it when it comes to performance and efficiency, more than I can say for Toasty old Intel.