With some VBA code, yes, this could be accomplished, but I think trying to do so is a bad idea.
You would be far better off having these items in their own cells if you want to implement some sort of color scheme. Indeed, if only four colors are to be used, you can still use Conditional Formatting even in Excel 2003: for the 4th condition, just apply the formatting normally, then use CF for the other 3. If none of those apply, the "regular" formatting wins out.
Of course, with Excel 2007, you can set as many CF conditions as you want...
