Yes, your instructions were good but I found myself using the instructions that came with the hitch as they were more than clear enough for me. This post did help greatly in my research for finding a hitch and understanding what was involved for the installation. Also I found that it wasn't necessary to remove the right tray access door.
I just wanted to emphasize that since the Lexus hitch is so expensive, $400, you can get the same exact OEM hitch from Toyota for $275 from your local dealer.