It can be accomplished within a few hours if the gear isn't broken. It is quite intricate work and my cluster took a bit of force to remove as it has likely never been out. You can make your own tools for removing the cluster as opposed to the ones that Mercedes-Benz sells. The thread link below has all the steps and is quite useful. I also changed out the two instrument bulbs. You will need a 3W 194 style bulb. Don't bother going any higher or you risk damaging (ie. melting) the cluster.
http://www.peachparts.com/shopforum/showthread.php?t=71691