I did the shifter knob on my '85 380SE a few years ago. As I recall, the consol wood comes out as Roncallo describes, then you unbolt and push the plastic cover piece up the shaft of the shifter, out of your way. There is a lock nut on the shaft that needs to be loosened, then you unscrew the lever like a bent bolt.
The female part that this is threaded into is spring-loaded, so inserting and turning the new wood lever is a lot harder than you'd think. I fought for over an hour to get it started, but it's pretty simple once it is in the hole a few threads.
I recently put up a thread on doing the dash wood pieces which you might like to peruse
560SL dash wood trim strip replacement questions