it's already supported.
Okay, how? :-)
I'm running 0.7.0 from Ubuntu, the options from the original Q3 patch (+set net_nov4 1 +set net_ipv6 1) don't seem to do a thing. I can't get a packet sent to IPv6 (e.g. by manually connecting to an IPv6 address) and the server only listens to udp 0.0.0.0, not udp6 ::. I could not find anything in the docs, on Google or in the Subversion log.