Thanks for your help PBG. No wonder the cover was so cheap! The person who sold it to me didn't know about the wheel retaining bracket either. Now that I have both parts I was able to install it and am now one happy camper.
I hated the cheap plastic silver cover that came with my S model - it looked like a large silver balloon, so I removed it and bought a nice Fan Blade Rim ($218) and hung that on the back without a cover (aka Jeep like). This was cheaper than buying the dealer's $360 black painted cover.
I see a lot of really interesting mods in posts, but you rarely see how much it cost and where did they get it from. Adding the links and prices just makes these types of forums all that much of a better resource for others to use.
The cost of the Fan Blade Rim ($218) and generic brand of spare tire ($80) were cheaper than the dealer's painted tire cover ($360), so I'd be more concerned about having my tire cover stolen, than the spare tire.
I think it looks better anyway. I put a coat of black shoe polish on the spare tire and it really holds up to the weather, because of the wax in the polish.
My RAV4 is leased, so the mods I do have to be backed off when the vehicle is turned in in July 2009. That sort of limits you to bolt on, screw on, or swap out simple mods. I still have the original spare tire and all the original sized Toyo tires.