if you just want to change the color of the lights in the background theres a couple things you can do. they both require disassembly of your dash and guage assembly. unless things have changed behind the scenes, my '98 guages took the same bulbs and my parking lights. they also came with little green "condoms" over them making the numbers etc light up, yes, green. i know the new tacomas have white faced guages and i believe the numbers light up orange. mine now show and orange like color and they are just the stock bulbs with the green cover removed, so i will assume that yours are just plain bulbs. you can buy new bulbs at any autoparts store for just a few bucks, there should be 4 bulbs behind your guages providing illumination. so one thing is to check for the little condom things and remove them, and the second is replace the bulbs. there are guage layovers out there somewhere im sure as well if you want to change the look entirely.
good luck