They don't have a specific TiVo/Dish box combined like with DirecTV.
I'm not sure if a stand alone TiVo box would work, probably.
But the stand alone TiVo boxes aren't worth it. The greatness of the DirecTV TiVo is the dual tuners. You can record 2 shows at once, or you can record 1 show while channel surfing on the other tuner.
The stand alone TiVos only have 1 tuner, so if it is recording you can't do anything else.
Standalone TiVos offer other features that DirecTv Tivos don't and most likely any new feature won't be offered on non standalone units. For example, the hyped Netflix connection.
I agree that the two tuner feature is great and I wsdh I had it. Personally I'm about to switch over to Time Warner and their DVR just to get the dual tuner and HDTV recording. Too expensive on DirecTV for the HDTV recording.
Does your Dish Network currently offer 2 tuners? So it would have the ability to record one channel with a VCR but watch another? If not, Tivo would never be able to just create a second tuner?