Walt,
With some time and a lot of patience, yes. 8)
In the newer versions of Adobe there is a replace color tool that allows you to use a color picker and select multiple colors within a picture. Once selected, you then simply alter the color with a RGB slide rule until you get it where you want it.
Sounds easy right?
It takes time and patience as you select all the color that you want to convert and then you must go over the picture and clean it up. I usually take any sharp detailed areas that I want left alone and create layers from these that can be left untouched then placed on the altered picture since your original will usualy lose detail when altering it.
http://www.freecomputeradvice.net/index.cfm/2008/11/19/Photoshop-Tutorial--Replace-a-Color-on-a-CarChris
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