Here's what I do with a W124: I have a small cheapo floor jack that I place under the frame rail on either the driver or passenger side. I jack the car up just a few inches, which gives me enough clearance to place my heavy duty Craftsman 2-ton jack in the center of the aforementioned crossmember. Then I jack the car up as high as possible and place 2 jack stands under the frame rail (NOT the jack pads) at even heights directly across from one another. I then lower the jack until the weight is fully resting on the jack stands, after which I raise the jack ever so slightly so that it then carries the majority - but not all - of the vehicle weight. The thought here is that the jack and the jack stands are sharing the weight of the vehicle.

Of course the whole time I have the car in P with the parking brake set and both rear wheels chocked both in front and in back.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280