Convert a full colour document to two colour in Indesign?

[Tyler Durden]

Hi,

I hope someone can help:

I have created a large full colour document in Adobe InDesign, but the printing is prohibitively expensive. As a result, I need to convert to two colour green and black (white paper of course). Is there a simple and quick way to remove all the other colours?
I know I can easily make it grayscale, but how to add another colour (green in this case) to the mix?

THANKS