Can you install MythTV on a Tivo box?

gfxguy writes: I recently took advantage of a program Tivo was offering where they replace an older Tivo with problems with a newer unit for $10.00. They didn't even want the series 1 back, they just sent a refurbished series 2. Now I'm wondering if the old Tivo (defective due to a bad modem, but I have an external one I was using) can be revived with MythTV. Anybody out there try this? Is there a problem with proprietary hardware, or are there other limitations? I'd imagine those old boxes are becoming quite common (and cheap off of Ebay). With a good MythTV setup from scratch costing about three times as much as a Tivo, it seems like it'd be a useful hack.