You supposedly can use pyTivo to send .tivo files. I haven't tried.

I made a patch for pyTivo that transcodes videos to an appropriate resolution based on the original video's resolution. With the currently released version of pyTivo, if you wanted your 720p videos uploaded at 720p, it would transcode 480p video to 720p as well. My patch fixes that.

You wanna give it a shot and let me know if it works okay for you?