Not much progress really. I talked to some a registered importer back in the states called Right Hand Drive Japan. I figured that, given their name, they would be the subject matter experts. I was sorely disappointed. The guy must have had a bad day or something because he didn't want to help out with anything. But one helpful piece of advice that he did give me was that the one part of the process that keeps most people from importing is the crash test ratings.
Basically, whatever car you're trying to import has to be slammed into a wall at different speeds in different scenarios in order to figure out whether or not it's safe enough to drive on US roads. The costs for these tests can be anywhere from $30K to $100K.
BUT, it is possible to bypass that part IF the manufacturer makes a statement in writing, saying that the US version (i.e. Lexus is200/300) and Toyota Altezza are structurally identical, except for the steering wheel being in a different spot. I did some digging around and found that those cars were manufactured at the same time in the same plant in Japan, so there's a pretty good chance that they are similar enough to by-pass the crash tests.
Normally, "petitioning" the manufacturer for this statement is part of the leg work that a registered importer would do, along with all minor mods that need to be done to the car (new fenders, bumpers, exhaust system, glass, etc...) and whatever customs fees that might be involved with the process.