On the 91 300SE I used to have I used Toyota semi-drying sealant (used for oil pans with no gasket) in place of the MB recommended stuff, actually 2 stuffs, and it held fine for over a year until I sold the car.

If you replace the cam seal, I found it easier to put the seal in the cover then the cover in place than to fit the seal with the cover in place. I think the manual says to do it the first way. The point is, it's easier to put the cover in place without the seal but you'll realize you're in a bind with fitting the cam seal later. YMMV.

Sixto
95 S420
87 300SDL