From that guide you linked
On your SD card there is a folder called "piforcetools" and inside that folder is a file called "piforcetools.py" If you edit this file in any plain text editor (such as notepad.exe) In this file you'll see lots of code but you'll also see a list of ROM file names and associated titles. If you're not seeing your game in the list after you've added it to the roms folder then chances are that file name is not on the file here. I would recommend keeping your roms named the same as the file names listed here, so that if you ever upgrade pi-force-tools you wont have to edit in your custom names all over again. You can of course add new files to this list as well simply following the format of the existing files listed.
There is also a list of IP addresses here, this is the list of addresses that you can select from the "change destination" option when running Pi-Force-Tools. The first IP address in the list will be the default that is always selected when you boot your Raspberry-Pi, and the other options are the ones that you can change too once the Raspberry-Pi has been booted.
"Instead of using a Cross-Over cable you would use a Network switch (any generic networking switch should do) with regular Ethernet cables, which thing plugs into which port on the switch doesn't matter.
Then you would assign each of your consoles a different IP address in the Network Settings menu. so in the guide we used 192.168.1.2 you could still use that for one of your consoles and then assign the others to 192.168.1.3, 192.168.1.4, 192.168.1.5, etc.
Once that's done on your Raspberry Pi you push the right direction button and then select the "change destination" option to select the IP address of the console you want to send the game to, then you push the left direction button to select the game to send.
Once the Raspberry Pi is done with the "Sending..." message and returns to the game list, you can select a new destination and repeat the process for the other consoles.