TiVoBlog has a great post from guest blogger Todd Barber. It walks you through taking a recording from your TiVo and extracting video clips from it on a Mac, even preparing those clips for transfer to a TiVo. While it is Mac specific, the general concepts would work on a PC, you just need equivalent software packages. If you have a Mac and TiVo, check it out.
(I’m sitting in the LV airport, waiting for my flight home.)