I just did the upper and lower gaskets, as well as replacing the sump pan.

For the upper gasket, I would suggest doing it with the engine out of the car, and probably upside down on an engine stand... It's a pain in the rear getting to some of those bolts along the forward edge, and near the front, just above the sump.
That being said, if you pull the crank pulley, it's a great time to replace the front main seal, and makes it much easier to get to those bolts.

I've heard someone else talk about taking the pan off while the engine was still in the car, and seem to remember that they lifted it away from the cross member to get clearance to drop the pan down and out. I question how feasible it is, just due to how far down through the oil pan and into the sump the oil pickup extends.

Best of luck with this, whichever way you choose to go.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...