Greetings fellow sway bar project cadidate.
I just completed this entire job a couple months ago on one of our 300SD's, (see sig below)
I outlined most of the process in this thread:
http://www.peachparts.com/shopforum/showthread.php?t=138289
Also, since yours is a 240, it will be inherently easier to do, since you have no false bulkhead, far less electronics/climate equipment/and so on in the way. I'll bet you will need to:
-Remove Brake Booster and master cylinder
-Remove hoses from climate system
-Disconnect Air Conditioning line (not sure on the W123, might, might not)
-Remove Battery and tray
-Undo any additional cables that may be in the way
-Jack up front of car if you choose (we did not, we did it with the tires on and car on the ground, thus proving this method possible)
-All the tools/wratchets/extensions you can muster
-New Parts: Sway bar, Sway bar bushings and brackets for the chassis, and sway bar bushings and bolts that connect it to the upper control arm. As well as anything else you wish to replace along the way.
-Take the air cleaner and such off the engine, gives more room to work.
-Be thankful you have a 240 and this will be SO much easier than on a W126
Enjoy and goodluck!
__________________
-diesel is not just a fuel, its a way of life-

'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)