One-first and formost, RETURN THOSE +4 PLUGS!!! They are little more than a marketing ploy and will make a mercedes car run quite porrly. The car was not designed to use those plugs and I promise you your vehicle will have problems with starting, idling, hesitation and a laundry list of other concerns. DO NOT PUT THESE PLUGS ON YOUR VEHICLE. I see cars fairly often that come in with these types of concerns, and after incurring charges to diagnose the problem, their unfortunate owners get the bad news that the overpriced gimmickery they or some unqualified independent shop put in their vehicle is the root cause. Get your money back and go buy some Mercedes-Benz plugs.
As for changing them, you can see where the suppressors go from the coils to the side of the motor. Simply remove the suppressors (if you're having trouble getting them out, MB makes a special tool that vastly simplifies the job, your dealer should have them or at least be able to order you one), and with the aid of you trusty snap-on extensions and U joints, break them loose and pull them out. It's about an hour's job on a six cylinder motor.