Thank you very much Samuel, I really didn’t know about Debian Boot. I asked on the Debian User list instead, and a few very nice people kindly sent me suggestions which finally allowed me to finish the installation.
I’d like to apologise once more for not knowing about the impressive number of mailing lists before posting here. I’ll only ask about accessibility here in the future, now I’m starting to understand how everything is being organised. Best regards and thank you one last time.
