If you have several PIX, you just copy the PIX config and change it should be fine. The idea is NAT translate the overlapping network to something else. After that, build up the VPN tunnel for both translated networks.
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...