After the previous firmware update of 1.02.06 (which I never managed to upload to my MyBook by the way), there is now a newer version 1.02.10. And for me this one worked when I tried to install manually!
Main update is the Mac compatability, see release notes.
The file and instructions for manual updating can be found here:
Instructions and Firmware and here are the Release Notes
Happy updating!
The Derny