Purchasing a Xilinx Platform Cable
To program the GODIL, it's best to purchase a Xilinx USB Platform Cable.
There are Chinese clones available on eBay for approx £20 that work perfectly well:
Download the Programming Software
To use the programmer, you need to download and install Xilinx ISE WebPack version 14.7 from here: http://www.xilinx.com/products/design-tools/ise-design-suite/ise-webpack.html
Be warned, this is a massive (~8GB) download!
The Xilinx site can be very confusing - don't download the newer Vivado Design Suite, as it does not support the devices used by this project.
Download the appropriate .mcs file from the releases section:
https://github.com/hoglet67/AtomBusMon/tree/master/releases
The structure of the releases directory is: /releases/$PART/$VERSION/$DATE
There are a range of mcs files to suit all the suitable boards for this project.
Go to the specific page for your FPGA board for information how to proceed further.