I have setup a CentOS 6.3 VPS with ONLY IPv6 access simply for testing at this point. It browses the Internet with lynx fine on most major sites that are IPv6 enabled. Yum does not seem to work though. Always tries to connect to an IPv4 mirror and gives an error. Is there a way specify an IPv6 mirror to yum?
Run through your mirror list, find a mirror which has a AAAA record in DNS, and specify that one explicitly?
For this kind of circumstance, my first approach would be to put a squid proxy on a dual-stacked (IPv4 & IPv6) host, and set http_proxy on the v6-only host such that outbound HTTP connections would pass through the squid proxy; the squid proxy will then use either IPv4 or IPv6 as appropriate for the requested destination host.
(Incidentally, this is a great way to give IPv6 access to IPv4 hosts as well. I was once surprised to discover my PS3 pulling video from Netflix over IPv6 in this way.)
I put a temporary public IPv4 on it and installed a single package with it. After that I removed the IP and a it did a full yum update without incident over IPv6.
My thought is on servers that do not require to talk to general public and mainly talk to other servers and admins or users that I know have IPv6 running them solely on IPv6 will work fine.