Well, I've finally decided to upload version 2.0! What with Opportunity about to rove off the current HiRISE frame there aren't really any excuses left to be made. I kind of abandoned this in July because I wasn't happy with how it was running but hopefully there will be some kml experts out there who can suggest ways to reduce the time it spends loading images (which will then feed into 2.* and so on).
It's an unholy chimera of a thing created using a combination of methods because the super-overlay tool I was using had a bizarre problem when I tried to create region files within a particular latitude band on Mars. Anyway, the final product more-or-less sort-of works. Just don't try to fly horizontally at high speed over the landscape because it might crash Google Earth.
It's available as a torrent here:
Torrent linkIf you don't have a BitTorrent client to download this with I recommend using
µTorrent.
Google Earth recommendations: If you have not done so and your computer is capable of handling it it would be a good idea to increase Google Earth's memory cache size to 500Mb (go to tools -> options -> cache).
It's probably best to remove version 1.0 first, otherwise it might prove a bit taxing.
To run, unzip the whole folder and open the file "MER-B map extension version 2.0.kml" located within.
Thanks again to James Canvin for splitting the HiRISE frame.
Some screenshots (with Tesheiner's route map):