If you happen to be using Notepad++, you can download [this handy XML file] that will enable syntax highlighting for your gcode files, just like the image at the top of this article. To import the file in Notepad++, go to Language > Define your language, click Import, and select the XML file.
@surfactant, in Komodo you would use Project menu > New from template > Create Komodo Language. That will prompt you for the necessary details which look like they’ll be available in that xml.
We don’t have a method of importing the language using that XML file.