The principal hardware difference between the kits is that the IGoL kit is provided with a 16 MHz crystal (and two helper caps). To convert an Octolively board into an IGoL board, begin by adding these three components in locations XTL, C5, and C6. No hardware changes are needed to convert an IGoL kit to Octolively.
You will also need the correct hardware to reprogram the boards. If you do not have a 6-pin DIL header installed on each Octolively/IGoL circuit board, you should add one at this time. You will also need an AVR ISP programmer that comes with a 6-pin ribbon cable, such as the USBtinyISP.
To compile and upload the software, you will need an installation of AVR-GCC and avrdude, which compile and upload the code, respectively. These are available, packaged together, in several different installers for different computer platforms. On Mac, we recommend Crosspack AVR, and on Windows, we recommend the MHV AVR Tools.
To compile and upload the firmware, you will likely need to edit the provided makefile to indicate your programmer name (e.g., "usbtiny"). To compile the code, enter "make all" from the command line, and to upload the code enter "make install" from the command line.