How do you make them? I know it can be done, as I've seen This Europe 1500 map (http://ron.heavengames.com/gallery/Mod_Album/aas) , and I also saw a World War I map. I couldn't find any tutorials or anything. Please Help!

There is some documentation on our website on how to create your own custom CtW map: http://www.bighugegames.com/ronx/downloads.html