I found some directions here:

http://www.peachparts.com/Wikka/M104WireHarness

It makes it look pretty straightforward, I'm rethinking sending my 300E2.8 to the dealer to have this done.

They quoted me about $1500 for the engine wiring harness, if I can get it done that easily for around $500, I'd definitely consider doing it myself

Does anyone have similar instructions for the replacement of the spark plug wiring harness? I'd imagine it'd be almost as easy. Should spark plugs be replaced at the same time (I had 6 new ones at the 150Kmi service just a few months back).

Most annoyingly I couldn't find either set of instructions in the MB shop manual CD's - any one know the procedure numbers in the manual for both sets of work?