They're plug and play, but you gotta get the correct lights. I have a halogen headlight car but I have LED rears (the socket for the parking lights have two little terminals on them - those power the LED tubes and make the connection for the bulb). Make sure you get the right set for your car - I emailed pics to Shmiedmann and they said they're looking into it. I think they're learning that there is a difference in the US cars. See pics here:
http://www.1addicts.com/forums/showthread.php?t=741038
I now have a set of LCI Blacklines that won't work on my car. Gladly sell them to anyone if you have the non-LED tube tails.