Setting certain network interfaces to Disabled?

I'd like to set certain network interfaces... all of them save Ethernet, actually... to be disabled in our InstaDMG produced image. I see how they are set to be disabled - specifically, within /Library/Preferences/SystemConfiguration/preferences.plist, and a key "__INACTIVE__" is appended to the specific network interface with a boolean value of true. I'm just not sure how I would recreate this within an InstaDMG image. Any ideas?