In general, in PB one cannot set up a lineup against a specific starter. However, if you look at your opponent's team, you can see what game a certain starter becomes ready to pitch. For example, I might scout my opponent, and see that Randy Johnson is currently "tired" and will need 3 more days of rest to be "ready." I will plan a lineup vs. LHP for games 4 and 5 to be ready to face Randy. That's about as close as you can come to setting up a lineup vs. a specific pitcher.
In general, I will set up lineups for each game vs. both RHP and LHP. If I see that my opponent does not have a LHP on his roster, then I only set up 1 lineup for each game. If he has only 1 or 2 LHP's, then I calculate when they will be ready to pitch, and for the games that the LHP is not ready, I submit 1 lineup, and submit 2 lineups for any game when there could be either a RHP or a LHP.