Verified answer

Both Tivos need to be Series 2 (version 2) or better and must have the Media Center update. They also need to be connected by a network connection.

If you have networked the Tivos properly they should give you the option of selecting shows from the other Tivo in the Tivo Central homepage.

Series 1 lacks this ability since it has no internet connection and Series 2 version 1 cannot because it is missing the required hardware to support other Tivo streams.