zywall with HE tunnel (native ipv6) -> bunch of tomatousb routers (bridged by zywall) -> IPv6 clients
See attached for config details.
Note that for windows to be ipv6 enabled i had to do :
netsh interface teredo set state disabled
netsh interface teredo set state client
try it first without these commands and then try it with if it doesnt work properly. linux is rock solid with default ipv6 enabled.
You need a tomatousb with RADVD not the new ones in the past few months which have it removed and are full of bugs. shibby 108 is decent and has it.