Thanks for the link, WS64.
I unzipped the files, copied them across to the root folder of my KT, and ejected it from the USB connection ... but it doesn't update. Even on a restart, the KT doesn't respond to the files. It's currently on 2.0.0 — is there something more I need to do?
(I tried launching the Kobo Desktop, and let my device sync to it ... it download the Desktop update, but nothing more. Do I have a hardware incompatibility, maybe?)