I worked with Buddha a loooong time ago (July 2015!) We were able to make Abe's PCB mill move with a Windows machine running Easel http://easel.inventables.com/users/sign_in . Note that at the time, Easel seemed to be ill-suited for PCB milling, but at least we proved it moved. We also ran Universal G-Code Sender from a laptop to the "old" controller board that was on the machine at the time (now replaced). https://github.com/winder/Universal-G-Code-Sender
Then Yev came along and did all the hardware updates. There's a nifty new modern driver/controller board attached, so most communication/configuration issues should be easier. There's also a Raspberry Pi attached in hopes that we can eventually set it up to be headless/wireless. All that remained at that point was for someone to figure out the complicated "toolchain" of software and setup the machine itself to cut (bits? spindle speeds? how to clamp the workpiece?)
The research I've done to date points at chilipeppr as the shortest path to success (but perhaps not the simplest/most user friendly?)
Here are some videos (Frank from Germany goes into detail about using Eagle in Ep 1, and actually mills the board in Ep 2.)
Here's a different end-to-end video: https://www.youtube.com/watch?v=DX0xGgSARj4
I hope this helps. I'm really interested in learning this-- if you know when you are going to sit down and work on it, let me know and I'll attempt to come meet you.
http://pcbgcode.org - I think this is the "old fashioned" way to generate G-Code from Eagle files.
http://www.pcbgcode.com/ - This page is an advertisement for a "wizard" program, but looks like there are some good hints and pictures here.