I just went through this exercise. I replaced all fuel lines, except the return line, and the mounting hardware. I wanted to replace the tank screen but the tank must be removed, which I didn't want to do. There is a rubber gasket between the tank and the body where the fuel lines go. (I didn't replace the return line because I didn;t have the right tool and I needed to get the car going.)
See group 47
http://mb.braingears.com/126_DISC1/program/engine_300SE.htm
Tank removal
http://mb.braingears.com/126_DISC1/program/Engine/103/47-100.pdf
I emptied the tank by using the fuel pump powered by a battery charger and a long hose to pump out the tank into plastic gas cans.
Caution: Fuel vapors are explosive. Use rubber gloves.
Do not plug in the battery charger until the charging clamps have been attached to the fuel pump. Observe the polarity, which is marked on the pump, and then plug in the charger. Empty the tank into gasoline containers. Have a garden hose ready just in case.
Then you can remove the tank etc.
See also:
http://mb.braingears.com/126_DISC1/program/engine_300SE.htm
Function group 07.3, sub FG 270 - 280.
I bought new everything except the pump and accumulator.
I will get to the return line and screen eventually and a new accumulator.