Using iPad as an extended display - using docking cable instead of wireless

I know that there are a few products that will let me extend the display of my Mac or PC to the iPad via wireless. While I haven't tried any of these products, I assume that they require my iPad and computer to be on the same network. This might be a problem if I connect to my corporate VPN from my Mac.

Is there an application that lets me extend the desktop of my Mac or PC to my iPad without dependency on wireless i.e using the docking cable?

thanks!