Yes you're thick. You didn't notice that I forgot to include the readme, and it's your fault I never included it later.
Seriously I do apologize. The file is so big that it takes jumping through hoops to take it out of Subsim Downloads and reinstall it, so that's unlikely to ever happen. Thanks to your question, though, I am going to write it into the description in the Download page so nobody will have to ask again.
As to installing it: In the SH3 Commander folder you'll see a folder titled 'Random'. Simply replace that with the 'Random' folder from the mod. You can use JSGME, but you need a separate JSGME setup pointed at Commander. It's easier to just manually put it in there.