Hi Rob,
I think a good place to start (whilst there is still a window of opportunity) would be to capture the communication between the official TiVo server and a TiVo.
We also have a good test regime still available to us by easily being able to force a OS update by fooling an OS mismatch between 2.5.5 and 2.5.5a
As you know, when Tivo dials in, they do a set of checks like validate the account, check the time etc. They also check if the OS version in the Tivo matches the OS version in their database.
If not, all EPG activity is skipped and the correct OS version is downloaded instead.
I have a couple of scripts I can give you to (if you don't already have them) which will enable you to switch the software version over from 2.5.5 to 2.5.5a (and visa-versa) at will.
If you want to give it a go, all you need to do is run the 2.5.5a script (if your tivo is normally ver. 2.5.5) and force a daily call. When the mothership see's you version is 2.5.5a, it will mismatch and it will force feed you 2.5.5.
Monitor the traffic and it probably wouldn't het be a bad idea to grab the files downloaded before tivo starts processing them.
To go through the test again, simply change the version back again and force another daily call
These are the sort of things I always wanted to play with but never found the time, so good luck
D.
Keeping the dream alive.