First, better to use a dichro, green modules are not all polarized in a single, sure and predictable way (and in some crystals, polarization scheme also change with temperature shifting), so a PBS is not the better way ..... you can anyway use an old dichro from a PHR sled, that reflect red and BR, but let pass green.
Also, "cyan" is a bit generic, as definition ..... also cause you cannot obtain a "cyan" wavelenght (say, 480nm ?), just summing two different wavelenghts ..... you can obtain a beam that "looks" like cyan, at the eyes, but is still a light mix, not a single wavelenght.
I've made some tests in the past ..... starting with a 30mW green module and a PHR violet (405nm) diode, you can mix the green with 60/70 mW of BR, and if at your eyes it appear too much greenish, you can increase the power until you get the color gradation that you want ..... it's all subjective, cause we don't perceipt the colors in identical ways ..... as example, i was seeing it similar to an Ar-Ion beam with 35mW of green and 110mW of BR, some other peoples can perceipt it "cyan" with some different level of BR.
It's all matter of "trial and test"
