gunzip it to / and run patch -Np0 < netcfg.wpa.patch to install. It will patch /usr/bin/netcfg for wpa support and it will add an example to /etc/network-profiles/template to get you started.
Any support, sugestions, comments, etc feel free to post here, email me [phydeaux37(at)comcast(dot)net], or post on the arch mailing list. I'd like to see some kind of wpa support make it into arch in the near future.
Looks like the patch will make it into the next initscript release.
Hooray for wpa.