I am in the same area as Cory dealing with Comcrap. Once I figured out the number for Comcrap's cablecard department the process is pretty simple. Simple enough I put a Romio in my own home. First thing I noticed was the TiVo picture blew away a Comcrap box. We hardly even use Apple TV now and use NetFlix on TiVO.
As mentioned, get the box online right away. TiVo suggests doing the updates once before the cablecard is installed. Then do it again after the card is installed. This is easy enough to do while you are doing other things on the project if you manage your time properly. I am also testing IP control of TiVo and so far in minimal testing it seems pretty stable. One less emitter to deal with.
When we get back from vacation I am going to add a Mini...