Procedure for engine mounts replacement on 1997 E420
 

Would someone give me guidance on the best procedure to replace both engine mounts?

use an engine hoist and lift the motor up for some clearance.

Seeing how crowded the engine compartment is I would install them from underneath the car.

You can lift the engine from the oil pan ~1/4" - 1/2"; anymore than that and you risk damaging the exhaust connections, fan blade, etc.

It doesnt take too much space to get the old one out; pending how collapsed they are you might need more room to get the new one back in.

what support would you use to lift the engine from the oil pan? a 2x4 across the oil pan?

I used a floor jack with a hunk of 2 x 4.

Lift slowly and have a friend help look for anything that might bind.

I have a hoist that I use. A cherry picker will work too and an engine cradel will work too.