Ok, so I added the two addresses under the rDNS section of my account (about 5 hours ago). When I go to http://www.test-ipv6.com and run their tests, I get this for my DNS test result:
Your DNS server (possibly run by your ISP) appears to have no access to the IPv6 internet, or is not configured to use it. This may in the future restrict your ability to reach IPv6-only sites. [more info]
Just to clarify, since I don't think I've actually seen this in this thread so far...
1) Are you wanting to use OpenDNS IPv6 service as a DNS *service* for your network? (You said you were using their IPv4 DNS service so I'm presuming "yes")
2) Are you using OpenDNS as YOUR dns service for YOUR domain? Right now, your domain that you own uses OpenDNS for name service? If you do a whois on your domain, you get back OpenDNS servers in the response?
The "rDNS" delegations in your tunnel setup page are you telling HE where to look for reverse DNS for the IP addresses in your domain. Don't point it to OpenDNS if they don't actually provide DNS for your domain, you need to point the rDNS delegations to whoever you're using to *provide* IPv6 DNS for your network, not who you use to *look up* DNS from your network.
Putting anything in the rDNS section of your tunnel doesn't change who the rest of the internet looks to for your actual forward DNS service.
If test-ipv6 is saying your DNS provider doesn't have IPv6 access, look to who your domain is using for DNS service (do a whois on your domain name), that's the info that test-ipv6 is complaning about.
Sorry if this seems needlessly basic, I'm just trying to make sure I understand that what you're wanting to do and what you're actually asking about are really related items, and it's not clear from this thread so far. :-)