Don't know! I have a bit of experience using Auto-It so I'm going to try and program it to tab through the old.reddit page and edit each post then move on to the next post. I assume using the edit button I could copy all text, then write it to a word document in something like an XML format which could then be imported into software.
But again, this is all based on theory, I haven't done any actual code or testing yet. Just based on previous experiences making simple programs to access websites and do specific things via a browser to mimic human interactions with the site. It's a very slow unreliable and inefficient way of doing things lol