I had to replace a dash light on my 2003 XJR recently and I would assume the dash cluster is similar for the XK8. The dash cluster does have to come out, it is not difficult, just quite a few steps. Hopefully you have access to a shop manual. Basically on the XJ, you move the steering wheel all the way down, disconnect the battery, then take off the wood trim. There are a few clips that hold the cluster in, once you get them loose, the cluster can be unplugged and pulled from the car. Reverse the process to put it back together. The clips, which are plastic, and the wood are delicate, so be careful. Good luck.
