Was W203 270CDI A'garde, Was CLK270CDi A'garde, Current Porsche BoxsterS, Mini SDAll4
If its the latest model then guess the easiest way, is to take a feed from the puddle lights in bottom edge of the front doors. Can't comment on whether there are puddle lights on the previous C208 model.
Failing that their is a DIY article on BenzWorld.org about fitting to a C class saloon, although this is much more complex than using the puddle lights. Link below to the article on benzworld