I've been doing this for the past year / so, but I'm not going to have a wired internet connection until I get fibre installed at my location - 6-8 months time - so if someone can help in the meanwhile it would be great.
It is pretty simple - download the completed projects from archive.org; wait for a cover to be made; when the cover is made make an M4B file with iTunes and Chapter and Verse (both freeware) and upload the completed file to Archive and notify the relevant admin (Currently Doslo21).
More detailed instructions exist on the wiki and I've improved (or so I think) the process so that it takes minimal human time (mostly computer processing in the background). Depending on the size of the projects completed I probably upload & download a total of 10gb per month.
If you're interested please post below. Next week I'll be able to put together more detailed instructions on my process.
** I've posted this here to make it more visible than in the M4B thread