I just fitted the plate in to my 2006 100 Series - unfortunately a little more annoying than on the earlier (or Lexus?) vehicles.
First the left and right vents are removed, then the four screws holding in the dash unit (which comes out in one piece - display, buttons, cassette, etc.). Then more screws to remove the frame pieces and finally four screws holding the cassette deck in the fascia. The plate itself fits fine. I could grab some photos if anyone would like to see, it's straightforward though, just need to follow your nose. Putting it back in can wait for another night