I've also manually updated a Nexus 7 (wifi only) using the same method as I used on my Nexus 10.
This is totally done at your own risk but it worked fine for me.
Since this is an update that patches the
already installed system I strongly advice against trying this on
anything but an non-rooted JOD40D device.
Just follow the same steps as in the Nexus 10 guide but use this OTA file instead.