I live in Florida, and compared to some States it is easy, and compared to some it is hard. It is also getting harder, especially if you are using an out of State title.
One way is to get a title from a similar car and use it to turn your car into "that" car. People sometimes say this is illegal, but the facts are, I bet a good percentage of the hot rods you see at any given show are done this way. We aren't car thieves, just car builders trying to get something we saved back on the road.
The other way is to it as a Kit Car, or Assembled From Parts. There are some limitations on usage for these types of cars though, something like you can only use them for club functions, shows, maintenance, etc........not daily driving. That sucks. I want to be able to use my rods as a car, drive it daily if I wish. Read the SEMA site lilgoneman posted, it will spell out the different methods for you.
Don