Right now on the back of my RV, strapped to the ladder is a flag pole.. no flag, though there is a Linksys WGA-54G on top of the post, somewhat weather proofed. and with a "Cantenna" mod to make it directional.
This feeds the Belkin inside the house (motor home)
Which is feeding (Among other devices) this laptop.
The Belkin router (And I might all routers) think the WGA is a cable Modem and treat it as such.
Set up is a bit of fun as I have to MANUALLY set the IP address for the wan side of the router in order to access the router's set up, and in a few parks something weird happens and keeps me from accessing the router.. though it works.
But you should be able to figure it out.