[R] Replace rgb with different colors for image display

[Bob Meglen]

I have created pseudo-color images from principal component scores derived 
from multispectral data.

I am using BiOps package stmt such as,

imgGetRGBFromBands(PC_1,PC_2,PC_3)  where PC_x are grey scale images.

I would like to display these 3 pc scores as rgb images where all three r g 
and b layers are replaced by other colors.
 such as orange , cyan, green.

I have experimented with colorRamps, RColorBrewer, rimage. Is there a way to 
replace rgb with other colors?