Just to change from red lighting to White and blue was pretty easy, no soldering required, I assume that the Gt has removable bulbs, that twist into place in bulb holders, so buy white or blue T5 led, dash bulbs of e-bay. Remove the bulbs from the original bulb holders and put the new bulbs in to them then twist and fit them back into place, see what happens, Any that don't light up remove turn 180 and twist back in.
You will probably have a weird looking mish mash of colours now, as the dials will probably have a coloured red or green film on the back in numerous places, so you would have to remove the dials, then carefully scrape this away with a so that any points where the light shines through are clear, not red or green. Hold the dials up near the bulb of a table light to test where the colours you don't want are coming from. I use a craft/scalpal set that you can buy from B&Q for £5. Only remove the film/paint from the places where unwanted colours are shining through, Just go very slowly and carefully, spend a day or two if you need to, to make sure you do it neatly. I use white bulbs for the main numbers and markers, and then anything else I highlight with blue film on the back of the dials. For this you can use either blue electrical tape from B&Q if you need to put highlights on the front of the dials, again you need to cut/scalpal these out of blue tape very carefully to fit where any printed paint would have been. And you can use it on the backs of the dials aswell.
I could start a thread on this with photos if anyone would think it worthwhile.