Alexadamz
Warlord
I've done it in RnF. It's not impossible, it's just incredibly difficult and requires you to have them basically surrounded with tall cities, Governor pressure, and a Heroic Age kickin.
I'm sure Eleanor will make it MUCH more likely to happen.
Good thing you can reject the city then and it becomes immune to your loyalty pressure. Some CS are too good to lose to that. If you loyalty flip a CS and then make it free again you become its suzerain? I have never done that, but I guess it works that way, no?