Amazon Unbox is offering the first episodes of Bionic Woman, Life, Chuck, and Journeyman for download now, free of charge, before they air. The catch of course is that Unbox downloads are not HD, so you may want to wait for the HD broadcast if you have HD.
Check it out online here, or go to TiVo Central -> Find Programs -> Download TV & Movies -> Amazon Unbox -> Free Downloads on your TiVo. Journeyman doesn’t seem to be there yet on the TiVo, but the other three are. You can download it online for now.
Note that these are purchases, not rentals, so they should remain available indefinitely once you’ve ordered them.