The easiest way is to partially remove the headlamp assembly. You do not need to disconnect the wires, since once you pull out the headlamp assembly, you can turn it so that the bulbs sockets are facing up. Once you get the vinyl strip and the screws/nuts out, then you can carefully maneuver the assembly out of its location.
There is another plastic tip at the top (closed to the top screw), that secures the headlamp in place, this tip can break and then it is difficult to correctly align your headlamp assembly. When you are removing the assembly, you need to carefully pop it out, and when you are placing it, you need to carefully pop it in before you put the screw and nuts.
Be patient and carefull when removing and placing back the painted vinyl strip. It can break easily and there is this plastic piece, at the edge, which can fall and then the strip will not fit tightly..
2005 ML 500
Black, 18" AMG Wheels, 285/60R18 Yokohama Geolander HTS + Bi-Xenons(+ Drew's e-code mod, though the reflectors rusted off and do not give out much light anymore), Yakima roof bars, Akebono pads all around. Former vehicle 2001 ML 320 with 108K miles, when traded, and a large repair/defect history. After all these years of owning my current 2005 ML 500, it is a major unreliable vehicle with a very large/expensive repair/defect history and has been like this since brand new.