I did it! Founded Christianity. Was hoping for Islam, but I'm not complaining.
I am going to try this strat later, but this was what I was hoping to do:
1) Workers - build roads to the flood plain that Aksum controls, so it has a better chance of getting an imported religion first.
2) Found Gondokoro by the Nile, build roads immediately after. Use the workers in tandem. Gondokoro is too slow for anything but a Library (with chop), then Research (if possible)
3) Both cities should start building libraries, but if a religion spreads to Aksum, switch to temples right away. Aksum is much better, with two cows and a sheep, and will grow with a priest. Chop if necessary to get that temple faster.
4) Once a temple is built, add a priest. You'll need it for Divine Right.
5) Switching to Research (both cities): Alphabet is important, so if you can trade with the Romans, Carthage, or Greece for it, do it. Egypt is protective of her hieroglyphs, so getting it from Ramses may not be possible. Both cities need research early, so it might be more economical to go straight to it instead of waiting for the libraries to finish (at least in Gondokoro). I could be mistaken on this, though...
6) Use the GP for Divine Right. If you can't get a priest fast enough, add a scientist (library) for Aksum, though this might weaken your chances of a GP. Only Aksum can do this, Gondokoro is too slow. Switch to Research early for Gondokoro, especially if Aksum gets a spreading religion.
Somehow no religion spread to me in my last game and I still founded Christianity - so I fluked my way to it. I hope this other way can net Islam - it was only ten turns before Arabia spawned when I got Theology, so the last game wasn't condusive to testing my theory. I've only had Buhen actually built (and flip) once in thirty-plus games, so I don't believe it's necessary or useful for this strat, though the extra research does help.
I'll keep you posted...