On my 190E manual trans, you just disengage and lift up the shift boot, then stick your two index fingers down the rear of the "hole" and lift up. There are two plastic tabs at the rear that should pop out (but it may take a couple of good jerks), then slide the piece back and lift.

You can then disconnect the electrical connector and push the switch assembly up to remove.

You could also go to http://mb.brainers.com and look up the actual procedure for changing the switches. It should be in group 54 electrical.

Duke