Are you sure it's even possible?
From what I understand about Networking and computers, if your Network Interface Card is down (i.e ethX), then it is impossible to send any packets outside of the machine. You might be able to ping the internal address, but that would probably be it. For everything else, I believe, it would be impossible. It's like trying to send packets out with an unplugged NIC.
Wake on LAN is another story, but the way.