Five photo limit...
If you already have the full cargo liner, you simply add this to your existing bits. From the web page, to looks like the liner has a Velcro strip across the back, and this would stick to it. You then would need to add the two small side pieces of adhesive-backed Velcro, and one long piece across the back.
In my case, since I don't have the liner, the Velcro on the bottom of teh front edge needs to have something to stick to. I had the similar Bumper Cover on my 4Runner, and it stuck great to the cargo area's carpet. But as noted on Canvasback's site, the LC200 has carpet that doesn't work with Velcro. So I need to add a 46" long piece of adhesive-backed Velcro to the carpet under the rubber mat.
This extra piece of Velcro is NOT included. When I ordered, I called to be sure that it got added to my order. When it arrived yesterday, it wasn't there. A quick call, and a piece should already be in the mail to me.
So, if ordering the Tailgate Piece ONLY, be sure to extra-emphasize that you need the extra 46" piece of adhesive-backed Velcro!
Thanks to Cameron at Canvasback for jumping on this for me. He happened to be the same guy that I corresponded with on a version for the Heritage Edition.
If you don't mind the extra coverage and interior fold, I'd go this route, as it covers the gap and the space behind the rubber liner.
[EDIT] Damn, those are large images! Sorry...