Only "Configured Tunnels" aka static aka proto-41 tunnels work, just fill in the details in the configuration menu and you should be done. There is no Heartbeat or AYIYA client in those devices thus those combinations won't work. (there was actually once a little discussion on getting it into it, but the GUI/configuration tools would require updates and that is apparently a horrible process thus it didn't happen, pressure Apple if you want, because it is a very useful thing to have of course...)

The Airport Express only seem to support local-link IPv6. The Airport Extreme, on the other hand, supports IPv6 routing and tunnels. Basically, you just open the Airport Utility, and: 1) go to Advanced|IPv6 2) Select IPv6 Mode: Tunnel 3) Configure IPv6: Manually 4) Enter in your SixXS, a) Remote IPv4 Address: PoP IPv4 for your SixXS tunnel b) Remote IPv6 Address: PoP IPv6 for your SixXS tunnel c) Local IPv6 Address: Your IPv6 for your SixXS tunnel d) LAN IPv6 Address: Your Subnet prefix (from your SixXS subnet) e) LAN Prefix Length: 64 Works perfectly with my SixXS 6in4, static IPv4 address tunnel and subnet. Downsides are 1) you have to completely disable IPv6 firewalling in order to get ICMPv6 on or through the router, and 2) there is no mechanism to add static routes in order to use any more than one of the 1000's of subnets you have with a /48 network assignment.