Forget about Tivo Desktop and Toast.

Try iTivo http://code.google.com/p/itivo/ which will download the file and convert it to your desired format (there is an option specifically for DVD), and then burn using iDVD.

BTW to upload to your tivo use the sister program pytivox http://code.google.com/p/pytivox/

Both are great open source programs that bundle up other great tivo utils (if only streambaby would work in Australia).

Hope that helps

Darryl.