iSiloXC is a command-line program, so double-clicking it will not do anything. You can only run it from the command-line (e.g., through a Terminal window [Applications/Utilities/Terminal]). But after unzipping it, before you can run it, you need to set the executable attribute using the command: If you want to learn more about the chmod command, do: Other than unzipping the files from the iSiloXC zip into some directory, there are no other installation steps needed.
Actually, you may not even need to run the chmod command, depending on what program you use to unzip the files.
In the NewsMac Preferences, you can probably just add the full path to the location where you unzipped iSiloXC, such as: