Is there a non-crazypants explanation of how to set this crap up?
Update: I got it working. The answer is "Fuck Google", and use OpenLayers instead. With that, plus these zip code KML files, I was able to pretty easily build an internal tool that displays our ticket sales on a map, based on billing address. It was like 80 lines of code (plus self-hosting 300 MB of geometry files) and spits out a zoomable map like this: