Comment 28 for bug 176125

There's an article which describes a simple method to activate it: http://www.heise.de/netze/hotline/IPv6-anonym-1100727.html

Just add a line to your /etc/udev/rules.d/70-persistent-net.rules:
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", RUN+="sysctl net.ipv6.conf.%k.use_tempaddr=2"