First let me say, this is highly experimental. That is to say, it works for me and few people that have used it, but no guarantees it will work as advertised for you.
Second. This is not supported by McAfee Support in anyway.
Now with that out of the way...
MWG6 (formerly Webwasher) had a utility that you ran on a Windows PC to create a small configuration file that had basic IP address information on it. When the appliance first booted, it would look for the config file, read it, and set the interfaces to IP addresses for access to the UI and continue configuration.
McAfee Web Gateway 7 has a wizard that prompts for the networking information when first booted. But it also has similar hooks into the boot process to read a config file from a USB stick and apply the networking information.
This utility creates the config.zip file that MWG7 uses with basic networking settings like IP addresses/masks, default gateways, DNS settings, NTP settings, and static routes.
To use. Run program and fill in the blanks. Save the config.zip file it generates to a USB stick.
Reimage the appliance, but choose the option "4-video console preferred".
Do not choose 1 or 2 because it won't read the file from the USB if you do.
Let the imaging process complete to the end.
Replace the imaging USB stick and replace with the one with containing the config.zip.
Reboot appliance (press enter).
It will pause for a few seconds at this point. Do not press any keys, just wait.
After the timeout, it will read the USB for config.zip. You can see the evidence of that here:
When the appliance has finished booting, you should be able to acces the UI using the IP address specified in the utility.
The main reason I wrote this was to load large quantities of static routes into a gateway instead of tediously adding them to the appliance in the UI. This tool lets you import or paste some flat files for static routes.