hi mate, its not hard really, just take the stereo out and take off the front, your left with a circuit board with about 30-40 "0805" leds, if you want to change the display you need to solder the display off where you will see about 20 more "0805" leds.
Just search for the colour "0805's" you want and start soldering, they are very tiny so its tricky, would also recommond doing 1 first and checking as there is no way at first of knowing which way around the leds go