rtsptogo is a RTSP server for TIVOs.
It has an html interface listing tivos and the contents. It then links to an rtsp stream of each file.
I have has success streaming SD content from a HD tivo to a nexus one, G1, vlc and totem over a lan. Real time transfers spead is needed from your tivo to computer and a real time transcode.
All the data is also available in json by making the same get requests with a Accept: application/json header.
A newish web.py is needed, ffmpeg with libx264 and libfaac support (I am using the medibuntu lucid package), and tivodecode. I have been using python2.6 older may work.
Put a config file in /etc/rtsptogo.conf, /usr/local/etcrtsptogo.conf or ~/.rtsptogo.conf then "python -m rtsptogo.main" or rtsptogo if you installed with pip to start it up.