I don't know what the ANC headset acceptable supply voltage range is. And I'd be careful with the 'power' seen on the GA microphone tip. Some of the GA mics use the tip for a PTT (push to talk) signal. It might appear to have a voltage on it, but this is through a sensing circuit that looks for it to be pulled to ground when the PTT is pressed. Connect that to an ANC headset power pin and 1) you won't get much power and 2) the GA radio system will see that as a continuous PTT signal. Not good.
The safest bet is to leave the mic/noise cancelling supply alone and use batteries. And to leave the GA mic tip not connected.
There was a Sennheiser document referenced earlier in this thread that had some better information on pin functions. But it appears to be gone. Perhaps wisely, as too much home brewing can be a bad thing. I have seen some adapters for sale on line for not many dollars. The certification of which should be verified prior to use.