Sorry to revive an old thread, but I came across this and thought I would share what I have learned. Im not sure if this has been "solved" or not but I came up with a solution. I have a 08 RX350, 08 LS460, and a 07 ES350, so I have experience with Lexus nav. I have only tried this on the ES, but if you depress the emergency brake just enough for the car to recognize it but to not engage it, it will unlock the controls. Hope this helps someone.
-Bill