Prevailing colors

You want to convert your colored file into one that uses just 2 colors?

Can you perhaps post a screenshot? 

Are you referring to something like Duplex printing?

Hex codes mean nothing in CMYK. They are just a different representation of 8bit RGB colors. That being the case, whatever you have in mind requires you to understand this first. Since you're only talking two colors, there's probably not much point ot get into that whole color management thing, which is mandatory if you want predictable print stuff. Instead I would simply grab a Pantone fan and figure out what best matches your green and assign it as a spot color. The other color is just black, anyway.

Mylenium