Unfortunately, all of your gauge cluster lighting consists of surface mount LEDs (aside from the lower warning lights).
I found a basic tutorial when searching for info for your interior lighting.
It's fairly good, though there is quite a bit of inaccurate information.
http://www.6speedonline.com/forums/996-turbo-gt2/316313-diy-guide-996-gauge-face-color-change.html?styleid=26