I'd say it is almost impossible to play now. I like to do it, but if I do, I make a scenario with a super starting position (basically: as much resources in vicinity as allowed), all types of terrain (mostly Lush), Mountains/Ice to protect all of my area but a small 1 tile path etc) And the last time I tried it without the restricted slaves and it went pretty good (not too far behind on deity). The reason I had to stop it in the early TH era was not because it was boring (the AI was fairly behind then thou) but because an overflow occured so that I can't increase my science output any further.
Only possible scenario where OCC still could work without "cheating" such a wonderfull starting position would be on VERY small maps with only 1-3 AI with 6 cities at most. And then of course the right settings like: Unlimited wonders, unlimited religious, no religious disabeling, no realistic corporations etc