No, it is not possible for you to access the underlying geometry that is used to represent these borders in Google Earth. Nor is it possible to use them separately in Google Maps as KML.
Your best bet would be to find a My Maps layer (if you can find one).
There are quite a lot of options, so I'll present a few generic ones:
Full Stack
Probably the most effort with the steepest learning curve. Store your data in some sort of database (typically PostGIS, but possibly SpatiaLite), use a middleware mapping server (like GeoServer or MapServer) to serve out a WFS which can be overlaid with Google maps using the Google Maps API. From a technical perspective there's no technical reason you have to use Google Maps here - OpenStreetMaps or Bing or even OrdnanceSurvey OpenSpace could be used.
The following resources may be helpful here:
I think pretty much all of the stack is operating system agnostic so should work on OSX.
KML
Convert your areas to KML, style them as desired, put them on a public web-server somewhere then use the Google Maps API (or whichever you go with) to show your data. I don't know much about KML creation/conversion but some searching should get you far.
Google Fusion Tables
Pretty much as the title suggests, use Google Fusion Tables. I don't know much about it so can only give a basic pointer, you may have to use this in combination with the KML one, but its designed for data visualisation and can come up with some very pretty stuff.
http://www.google.com/fusiontables/Home/
Note - If you are going to use Google Maps, they do cost money after a certain number of impressions.
Best Answer
Could be a cloud.
Google try to filter these out, but not too well in this case.
Have not found any links to back this up, but I do remember reading about it on a post that was looking at the possibility of rendering a 3D real-time cloud layer.