bcool
Deity
I tried the spy thing into culture. It takes 3 espionage points to spread 1 culture, so you would need ridiculous espionage modifiers to pull it off. You will also need an army of spies, and between 10,000 and 100,000 espionage points to spread 30,000 culture. I wouldn't attempt it on normal speed. It is just too slow. To get the necessary espionage you have to go all the way to communism.
We can get that espionage without communism I would think.
If we use espionage to get lengendary in one city, wonders to get the other city legendary (with cathedrals in that city only), and great artists to get the last city lengendary then we could use the slider to produce espionage.
So the entire empire could put it's commerce output into to producing the necessary espionage. Since we will probably get nationalism for the hermitage it isn't too far from constitution for jails. That means we could have +50% espionage from jails in key cities and we could run nationalism for an additional +25%. Plus you can run spies in the cities with jails and possibly all cities with a courthouse.
So for an empire with 20 cities, 20 courthouses, 10 jails, 40 spy specialists, 100% espionage running nationalism we could get about 1000 espionage points per turn. So for 50,000 culture and a discount of 0.25 on espionage missions you need about 37,000 espionage points and at 1000 espionge per turn thats 37 turns. (and an army of spies)