For a quick a dirty image > adjustments > colour balance or hue / saturation.
That's what I do when i'm lazy. How hard would it be to use the wand selector and fiddle with the tolerance numbers till it only selects the bits you want to change... then you can do as above.
yeah as hugh said - its pretty easy just select the part of the layer you want edited, and use the adjustments to mess it with colour balance and hue/saturdation.. the hue is the easiest way to mess with it.