i'm making the assumption you're referring to the trail
i've looked into it. looks like a fun way to spend a couple of weeks. the fall '13 issue of OJ had an article about some guys that went south to north. i can't remember if they stuck completely to the TAT or not. i'll have to look at the article.
an old friend from san diego and i have been talking for years about doing it, the 'shadow of the rockies' portion, then continuing through the Great White North into Alaska.