CO2 extinguisher or open the cap nuts on the injection lines (17mm on a
61x, 14 mm on a 60x engine). MB recommends loosening the lines.
DO NOT use a towel on a turbo equiped engine, it WILL get ingested
(possibly along with you fingers or hand).
Have the wrench in your hand when you start the car the first time --
better yet, have it on #1 injector! Probably won't have anything
happen, but I know two people who had a Benz diesel "run away" -- on
got covered in fuel by opening the injectors, the other lost an engine.
Peter