Thanks for your help, gentlemen - it's appreciated. Unfortunately I keep drawing blanks.
Lexus or igo interface? Lexus. I don't have the lane directions shown in the image on that page.
The box in the boot is definitely not it. It's actually a little bit narrower than a DVD, has a screwed-on cover on the side facing aft, big brackets at either end, and a very big connector on the side facing under the back seat. I think it's part of the energy control system. See attached image. It's nothing like the DVD player in my previous RX.
Whirlpool: Yes, I assumed my DVD drive was in that location (as per the photo a few posts above). However, on removing the cover there is no DVD drive in there - just an empty space. This is particularly galling as I was going to open it up, but saw the image above, thought "that's the same as mine" then went ahead and ordered the disk. Luckily I only got V25 which cost $50.
If either of you could use the disk, it's yours to pickup in Perth (northern suburbs) or $10 to cover postage. I won't attempt to upload it as my internet is both slow and erratic.