OK!
Think I've managed it.
I used the HP tool, already had it on this PC but didn't consider using it
Formatted as fat32, then copied the files over as I had before.
I now get the "CYBOOK GEN3" loader screen with the image, then a
"..." with a picture of the cybook next to it.
It has developed a tendency to turn itself off, but I'm going to leave it charging today and see how it goes...
all! I may update the method if you don't mind Derek/Roland? Just put in the bits I've got, and maybe upload a ZIP file with all the necessary files in one place?
Regards,
Simon