Ok, figured out that I had to not use the new "mirrorlist" scheme, but the old "baseurl" scheme within the repo configuration file.
in reply to Re: Mirror a package repository on the fly.
in thread Mirror a package repository on the fly.
So, it appears to work, but is only caching some .xml files, not the downloads themselves. That doesn't make much sense to me, if it's able to save the .xml files, it should certainly be able to save the megabytes worth of actual package files.
Seems I'm talking to myself at this point, but if anyone is actually reading this and has any suggestions, I'm listening.