There are two ways to do 3D. The one used by cable just squishes two pictures into one frame, either side by side or top and bottom. The TV then separates the two pictures, stretches them to full screen, and displays one for each eye. This method is compatible with any device because the signal is no different then a regular TV signal. The TV is just doing special processing to make it 3D. The downside to this method is you end up with half the vertical or horizontal resolution for each picture, so you lose a bit of quality.
The other method, used by BluRay, is an extension of the H.264 encoding standard called MVC. MVC encodes each eye as a separate, full resolution, stream however it shares some compression information between the two streams so that the resulting video file is smaller then if each eye was encoded as two completely separate video files. MVC requires special decoding abilities and I'm not sure if the TiVo Premiere has a decoder capable of doing MVC or not.
So to summarize if you record something from cable that's 3D it will work fine, since they use the first method and it's definitely compatible with TiVo. However if Netflix decides to use MVC for 3D then it will only work on TiVo if TiVo has a decoder chip capable of supporting MVC. (I honestly don't know if they do or not)
Developer for VideoReDo