linux - How do I deploy IPv6 within a LAN using a Debian based router and prefix delegation?

My ISP started using DHCPv6, which means with this /etc/network/interfaces...

auto lo eth0 eth1

iface lo inet loopback

allow-hotplug eth0
iface eth0 inet static
    address 192.168.0.1
    netmask 255.255.255.0

allow-hotplug eth1
iface eth1 inet dhcp
iface eth1 inet6 dhcp

... my Debian Wheezy router finally gets an IPv6 address assigned (yay!).

But what do I need to do next in order to get my router to assign IPv6 addresses to all the workstations within the LAN?

With IPv4 all I had to do was to enable the DHCP client on the WAN interface, assign static IPv4 addresses to the router and the workstations and finally set up NAT (I used iptables -t nat -a POSTROUTING -s 192.168.0.0/32 ! -d 192.168.0.0/32 -j MASQUERADE for that).

With IPv6 there is no NAT. I've looked into radvd and isc-dhcp-server, but both seem to require a prefix set in their configuration files (ie. a prefix that doesn't change). My ISP however seems to provide me with a new prefix every time I reconnect.

I'm really lost.