That's been tried and it doesn't work. Also, it has been noted that DD 5.1 no longer works either, just Prologic.
DD 5.1 no longer works? Jeez, as if I needed further demotivation to keep me from getting the Tivo software when it becomes available. That one makes absolutely no sense. Although more likely than not its just a software bug that they have to fix. If it is something that they did on purpose and intend on keeping in the software then that's really stupid and makes no sense.