It would be a nice feature enhancement to allow the selection of mirrors (placed into /etc/portage/mirrors) from thirdpartymirrors to prevent portage from auto-selecting a mirror in another country when more suitable mirrors exist closer to the machine attempting to actually grab the distfile. Possible options would include parsing thirdpartymirrors and allowing the user to select which/all mirror://$site they want and allowing them to grab -s$n of them as with mirrors being selected for make.conf.
This has been brought up before, and it was decided that there is no benefit. It is possible that my understanding of exactly how thirdpartymirrors behaves. I'm open to suggestions, so feel free to reopen this bug or (preferably) get in touch with me on irc.
