The headlamp multiplugs are different so they won't plug straight in. The cars with xenons use auto levelling from sensors on the front and rear suspension wishbones but the normal adjustment wheel inside the car will work as normal with them.

It would be a case of getting a section of loom with plugs on the end and soldering them on to your original loom to get them to work. Best person to speak to would probably be Dojj, he knows the mk3's inside out.