This is something I've been looking at... but thus far, no joy. I've figured out how to change the rotational speeds of existing FL objects, but that's about it thus far. More news if I ever get back to cracking that.

I don`t have the answer, but i did think of a solution for a base. The base is exported in two parts. Both have the same mount position. Then the dockable part remains stationary and the ring rotates around the middle.
I`ll give it ago sumtime soon, but haven`t created any new bases yet because I`m not too sharp at sur files and my ideas tend to be a bit complicated.

Perhaps look at Ft. Bush - it has some rotating parts

You could just make things spin like the planets. I once made a moving asteroid field out of that.