First, are you sure its not the speedo cable?

If you are sure, then you can get it out by prying on the unit. Yes there is a special tool (hooks made by mb), but you do not need them. a couple of small flat screwdrivers will work. just becareful not to pry against the dashboard or you will put a nick in it.

anyway, pry the whole unit out, then unscrew and unplug everything making a mental or peice of paper note on where things connect. Then you will see about 8 screws on teh back of the unit, remove the clock, and tach, and so forth and you can take it out.

Goodluck.