I've been digging around and it looks to be a lot more difficult than just changing a bulb.
From what I've read on
THIS post the instruments are lit by SMD LED's which are soldered onto the circuit board.
Now if you're a wiz with a soldering iron and have a steady hand I'm sure its easy to remove and replace the dead LED's and I'm going to have to try it as its my speedo that not lit so I'll let you know how I get on...