I found another article about this today, which DOES mention some specific routes and cities he passed through. Apparently he used "scouts" in different places along the route to check for potential hazards, cops, etc. shortly before they came through in the AMG. Also a lot of electronic assistance stuff - reminds me of the Japanese team in "Cannonball Run":
Atlanta man shatters coast-to-coast 'Cannonball Run' speed record - CNN.com
It'll be interesting to see what the panties-in-knots, uptight bureaucrats try to do - if anything.