Ah, really old thread. I wondered how I never saw this before and there are 5 posts that it claims I read
My advice to pull this one off would be to set the option for "require Complete Kills" and gift yourself Acheron somewhere that the AI is unlikely to go and which is unreachable by normal means (like the 3x3 island they talked about earlier, one plains tile & 8 peaks in the middle of the ocean).
Since Acheron has no movement, it will never stop to ask you for any input of any kind, and since you don't have a city you won't need to decide on new technologies to research, and shouldn't get disturbed for any trades/demands