How does one replace this part...?

Say Hi to Raylan

 

Your best solution would be to find the parts you need in a junk yard. Used parts will be a fraction of the new part cost.

 

Driver's side pieces should be pretty much a mirror, that'll help. I think the biggest hassle will be getting the wheelwell liner out and replaced. It'll help to jack up the corner and remove the wheel, pretty much necessity. Try to get some spare fasteners as well, looks like a few are missing from your pics, and some may break during removal. Wash them before re-install, it helps keep them working smoothly.

I don't think I've completely removed front wheel liners on ours (sure I'd remember). I've taken it partially off, just to see if grit was accumulating. It's got a lot of those push in fasteners.

 

You have a nice car. I would go to Toyota and have them order and replace the parts and have it done right.

 

-1

That seems silly to me. This repair looks dead simple and the dealer will charge an exhorbitant price.

Here's PriusChat, a resource to help people research and take care of their cars and educate others on how to do that and possibly save money. Doesn't make sense to me that posters would recommend going to a dealer for this simple stuff.

But it's your time and your money and only my opinion.

 

Or just get the parts at the dealership.