I had looked at that page a few weeks ago, but shied away from it, because I dislike Chrome so much. But I'm trying to do exactly what you're describing, salvaging as much as I can, even if it's in pieces.
I hit a wall with both PG Offline and the Chrome application, so I'm in a bit of an uncomfortable holding pattern at the moment, considering the looming deadline.
With PGO I get a perpetual login error.
And with the Yahoo Messages Application I get "Failed to load extension - Manifest file is missing or unreadable - Could not load manifest". I do see a JSON file named manifest in the folder, but have no idea if's readable. I wonder if I followed the instructions about what to do with the zip file correctly. The instructions talk about creating a directory and copying the files there, and I don't think I know what that means. I figured I was just supposed to unzip it, and then point Chrome at the unzipped folder, and that's what I did.
Any insight you might have acquired while you got it to work?
In the meantime I'm going to request another batch of Yahoo data, and hope there are additional puzzle pieces. Yahoo sent out a mailing that we can request our date until Saturday night 11:59pm PACIFIC, and that they won't delete the archives until they've fulfilled the last open requests. I'm hoping that requesting more data is a way to extend the archives just a bit longer, to buy time to download the rest.