You should use a a supported 3rd party app like Steven suggested. You could also configure URL filtering, explicity deny the domains you want blocked then change the allowmode to permit. This could cause high CPU utilization, so proceed with care. You can reference pg 435-436 in Richard Deals 'Cisco Router Firewall Security' for more info.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...