They put out the inactives a few hours before each game and I get them by having the Seahawks app on my phone. They send out a notification of the inactive players through that. I believe they are usually put out through twitter, and can usually be found in a thread in the gameday forum on this site as well.
It's usually up moments after it's officially released at any of the other places, so it's usually a good place to start (at least for the Seahawks' list)