I was lucky once & built all the wonders at empire level (in one city and a GOTM to boot!), but never at deity. A couple of thoughts that I have yet to try include adjusting the starting conditions -- barb level, world age & temperature, etc. I think I typically see the ai starting wonders after their third or fourth city, when they are not at war. Also, dont know if the particular ai makes a difference (at prince level, the babs will start a wonder with as few as three cities, but I dont recall the Zulus doing so -- of course, the Zulus will have four cities before the Babs have three so it may not matter.) I also havent paid attention to the ai choice & abandonment -- ie are the Mongols more likely (or the Vikings less likely) to abandon than switch when a wonder is built out from under them?
Another point -- it seems to me that the 200-shield wonders go the fastest -- typically I see Pyr, Col & HG as the ai first choices, with LH & 300 shield wonders coming second -- but if the first wonder surge is long, then the switches begin & can continue through half of the next batch. (This may mean avoiding some trades
) So if you can somehow get a situation where the ai is stymied to an extent, then you have a shot.
Smashs second thought of course has merit -- if you can conquer the world before an ai gets a wonder, then you can build them all with no competition -- but I think that that is a different game.