Have and modders seen this thread? Any thoughts yet on mod-built residences? I haven't seen any but I don't know how the modding is going yet.
As the CK isn't here yet, editing cells and landscapes is notoriously difficult, if not impossible since the current modding is basically just Hex and Raw code for things in the game. The easiest things to mod at the moment are external things like textures, sounds and (slightly more difficult) models where you do not have to go poking around in an .esm or .esp file.
I'm sure after the CK pops out (hopefully) soon, there will be one within hours. If not several, I certainly know I will make one for myself. I spent hours down there collecting every single Nirnroot that I could get my grubby mitts on. Exploring every nook, cranny and building for Geode Veins and fat lutes.