They'll do a truck roll to bring you a CableCard & a tuning adapter. You might want to pick up a short printer type USB cable too for your tuning adapter (I think it is an A-male to B-male cable. The tech that came out to install mine didn't have one, and was baffled as to why the tuning adapter wouldn't connect properly with the TiVo. I told him the diagram that came with my TiVo showed a USB connection, he was like "I've never done that before". When he was outside talking to the office I went and found a cable, plugged it into the TiVo and tuning adapter and all was well.
The pairing and authorization can be a challenge, but I believe they've gotten better at it. Once you get it working you will be VERY happy. I actually ran the guided setup on mine when it arrived before the cable guy game to download the channel lineup and all of that. You can do that without the cable card. I even set my channel list before I got the card. It only shows the HD channels in my case, and a few SD channels I want to be able to pick up.