Just a quick update to let future readers of this topic know what I've found.
The child restraint anchors are available from Toyota spare parts. They are just under $50 each for the Tarago (2002 model) which is of course outrageous to charge this much, but I'd rather my children be safe. They come in kit form with the plastic cover included. The anchors simply screw into the rear of the second row seat frame - pretty easy to do.