The process is the same (and not to bad if done right apart from the time it takes)as importing a car; but one major point I missed that may save others time is to MAKE SURE that the trailer / boat / caravan is bought and registered or invoices are in the SAME NAME AS THE CAR you intend towing it with.
Mine was not, with the car being UK registered in my wifes name (and hence customs imported it in her name), and the CRiS caravan document was in my name. MAJOR CRISIS
We ended up sorting it by having to make a written statement of "sale" of 10% of the caravan to my wife..........crazy. This had to be witnessed and recorded in the Tax Office (it also cost me 5.40 Euro !!!!), and two hours !!!!