cmyk colour cant really get close to rgb colour as cmyk is dye colour and rgb is using light to present colour, it must more brighter and vivid... i have an experience to use spot colour to replace rgb but end up i have to give up... not up to my expectation. i heard got kind of printer that can go 600dpi, you might give it a try, i saw the sample, it really look like real and very contrast :) search it in google, you will suprise :)
