Schumi,

If all you want to do is to replace the "stick", the upper part of the lever that comes up through the rubber boot, you don't need to take out the whole shift lever assembly. Remove the wood (for reference, see the pictures about halfway down this page just after the text titled "Step 3 - Head Unit Removal":

http://www.peachparts.com/Wikka/W124Stereo)

After removing the wood panel you'll see 4 screws holding on the rubber shift boot and frame. Remove the screws and lift up the frame.

At the bottom of the stick you'll find a lock nut. Use a 14mm open end wrench to loosen it and simply unscrew the shiftstick. There's a spring that will try to keep the whole thing pushed to the left, but it's not very strong and you can hold it wherever you need to with a couple of fingers.

Hope this helps,

Gary