Yeah, its pretty easy to change the bulb at the back of your temp display.
Just have to unscrew the 5 screws holding the top of the dashboard on, then undo the 2 screws holding the main dials in, carefully pull the clocks towards you and reach round to the back to undo the speedo cable (just squeeze the white collar, and it should unclip), then if you unplug all the cables at the back of the clocks youll be able to get in to change the bulbs or bulbs (cant remember if theres 1 or 2).
Then just plug it all back together and youre back in biusness, DONT forget to clip the speedo cable back in.
And you cant change the colour of the bulbs as the light shines through an orange filter.
Hope this helps
Dave