-You need to enable in Advanced "Enable IPv6 Support".
-Under WAN, choose AICCU. Enter user id, password and Tunnel ID including "T".
-You need to make a separate request to Sixxs.net for a subnet.
-Under LAN check "static IPv6", enter the "Subnet IPv6", also called "Prefix" from Sixxs.net, /64 and check "send IPv6 router advertisements". Do not enter the "routed to" or "IPv6 Them" given to you by Sixxs.net.
-Under IPv6 firewall rules make a rule to allow everything on the LAN.
-Reboot m0n0wall and your computer. You should be able to access IPv6 sites!
http://forum.m0n0.ch/index.php/topic,2642.0.html