It is reasonably easy to replace and the dashboard doesn't have to come out.
Remove the radio (if it is a BMW radio you may need to unclip it using coat hanger wire down the 4 holes).
Pull out the clock (carefully pry the face plate off with a thin flat screwdriver which will expose the clips behind that hold the clock in) and the switches next to it (hazards, blanks, etc just pop out by pushing from behind).
There are two screws at the top (accessable through the clock hole and one of the switch holes). There are another two screws at the bottom, underneath.
You also need to remove all the ventilation knobs, then pry out the face plate panel in the slider area which will expose another two screws.
It should then come out and you should be able to remove the temp and fan speed controls.