two colors, change each color by script (example: black/white striped car)

ok, so lets say I have a car like this:


http://bjmotors.biz/images/inventory/2009DodgeViperSRT10ACRWhiteBlackStripes_0639/large_01.jpg

and I need to change each color independently and dynamically, and I cant use two objects because is the car body, so I need a shader (I guess, if I could just change color by tone to the texture using any shader that would be great) that allows me to change color to the texture by alpha or by tone.

right now I have a black and white striped texture, I asume I need a special shader but no idea where to start.

any pointers?

thank you.