Well, if you want three channels, use RGB and then color shift as necessary to achieve your results.
If your channels are the colors you mention above, however, it’s going to generate some wacked colors in the final images.
Are you trying to take a channel and use it’s information for an actual image?
You can also use the various channel ops (add/sub/multiply etc) and create a new channel using the C and M in cmyk for instance and then just delete the C and M channels.
Why do you need to do this? Maybe if we knew what your end result is going to be, we could get a better answer for you.