The mod is dead, but, if you type /biomes 10000 and wait for it to search, you can find a city biome that way. The map that pops up is orientated north to south, with the center being where you are.
But again, this mod is DEAD. the newer version is on the new thread linked above, but, it doesn't have the cities, as that was technically another mod, and the new maintainer doesn't have permissions to continue it.
Locking this thread as pestering the mod creator, who hasn't been around for a while, for updates will not help the current situation. If the mod creator (GiMoe) wishes for the thread to be unlocked, please send me a private message.
For those of you looking for an updated version of this mod, you can find it in the link provided below.