No, there really isn't any way to know more than about 30 minutes before each game. The Yahoo stat tracker if you buy it will show you the lineups, and so will their baseball scoreboard, but that only updates 30 minutes, maybe an hour before each game. That is usually because a manager doesn't finally decide what lineup he is going to use until that late before gametime, due to last minute scratches, injuries, etc., so there isn't much you can do. You could sit on the StatTracker and check out the lineup and if you see that a player isn't playing, sub in another player off your bench, but that will only work if both players are playing a game at the same time, which doesn't often happen with west coast games, etc.
Also, in general, catchers play only about 120 games a year max and get every 4th or 5th game off, simply because the position is so demanding and wears down on the body. One way to almost certainly guess when a catcher won't be playing is that most managers won't play a catcher in a day game after a night game (most often Sat night, Sun day). Otherwise, there's not much you can do about using up all your games, especially at the catcher position.