ipv6 on hotspot

hi all

i have a RB450G and about 300 client

the diagram is like that … Main router RB750GL (loud balance 4 ADSL PPPOE lines ) “ipv4” 192.168.1.1/24 ==NAT==> squid “ipv4” 192.1686.0.1/24 ==NAT==> RB450G runs a "hotspot"on ipv4 172.20.20.1/24

i want to make the RB450G hotspot on ipv6 INSTEAD OF 172.2.0.20.1/24" for security issues like netcut and so on "

can any one help ..???

thanks any way ..

still waiting ..!!!