I spoke with the local MB Service manager yesterday and he told me that the torx head size is #30 and all you need to do is remove the key from the ignition and carefully remove the bag after removing both screws. he said as added safety you could disconnect the wiring but he said he hasn't of anyone setting off the bag when trying to remove it. I am not sure if all MBs use this size screw but its worth a shot. He hadn't heard about a tamper proof screw for this application but said that may be the case with newer cars.
P.S. I tried it last night, no problems but you will need a fairly long torx head screwdriver, i used one from craftsman. Ken

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Ken
87 190E2.6