Ive done it three times. This is what you need...
A bill of sale
An MoT
and stay in good contact with the shipper. We used Wilmhuasen something or other. The lady that you'll have to deal with her name is Amy and she can be tough. There are rules but, if you contact the customs agent...I forget his name. Portly bald fellow (make an APPOINTMENT! and dont be late)
My only warning to you is that these vehicles can be absolutely trashed. Most of the times, these vehicles are just repainted (sometimes rather poorly) and the frame should be replaced almost immediatly...
After you get it over here, contact the vehicle registration office and a plain clothes state trooper must come out and inspect the vehicle and ask you a few questions (to make sure its for personal use and safe).
Make good with all the guys at the ports and they WILL take care of you. Also, they are ALL union guys so get there early and make sure they arent on a holiday of some sort. You WILL wait almost all day for the truck to get off the boat. Most of them are transported VIA RORO (roll on roll off) so if they cant drive it off that aint happening.
Anyways, Ill try and think of some more stuff but, there is a start.
Good luck,
Matt