The recent 6.1 update to Airport Utility now lets you edit the IPv6 configuration of your various Apple Airport devices. The new 1.1 version for IOS also supports editing IPv6.
In the Tunnel section there is a new field called ‘IPv6 Delegated Prefix’.
If you are using Hurricane Electric’s Tunnelbroker for IPv6 – you can enter your ‘Routed /64′ address there in its entirety.
Not exactly sure what functionality this adds to the Airport device however. Everything on the home network functions as it did before.
[Update 3.13.2013] – Apple has posted a support page with official instructions on how to configure Manual IPv6 Tunnels in Airport Utility.