Well, if the LCD was fast enough, but its no where near fast enough, but if it was....Trag, we need cap kits and colour LED backlight kits. It would be cool to have different colours.Replace the inverter just for giggles too.
you could use RGB backlight to do field-sequential color and it would appear that the mac would have full color. But the Video adapter doesnt support it, and neither does the LCD response time.
I did this very thing with an old Mac SE CRT and a color-wheel. built a full RGB color field-sequential VGA monitor. Same rule would apply with LCD, if you used RGB backlight instead of a color-wheel.
But the LCD response time isnt fast enough to be able to switch RGB video signaling without extreme flicker.