Junkyard maybe? Not sure if it requires a different harness or not. I know on my '06 I have to go through the setup buttons on the dash to change them and I doubt swapping just the cluster will add that to the menus. You may want to look at some reverse glow gauges or something similar instead of trying to swap. In all honesty, I use 2 colors on my dash and about 90% of the time it's just the one. I made a custom white color (as lame as that sounds) and the red and rarely switch, so the cool factor of the custom colors kind of fades pretty quick to be honest lol.
My understanding is taking a non premium GT and making it a Premium with the mycolor feature is insanely expensive if you can even make it happen. Would need a PCM flash from Ford, full kit installed among probably other things.
I don't think anyone who has tried it has been successful.