I don't know if anybody else has said this yet.. but
You can't use ADB commands without enabling USB Debugging under Settings > Applications > Development > USB Debugging..
You also MUST install the USB LG drivers on Windows.. On Linux or Ubuntu, no drivers are required.
As for enabling USB debugging, there is NO command for enabling it (as far as I know).. You must enable it manually under Settings > Applications > Unknown Sources..
AGAIN, you there is not a command for enabling USB Debugging for ANY ANY ANY Android device... Even if there was, you wouldn't be able to use it because you have to have USB Debugging ON in the FIRST place to EVEN USE ADB....
So.. you can not use ADB commands without MANUALLY turning USB Debugging ON in Settings > Applications > Development > USB Debugging (Tick the BOX)
Drew, thekraven, me2151, or any other developer will tell you the same thing..