Go to a 3 or 4 man rotation, move your 5th starter to LRA (or LRB) and drop your worst relief pitcher off the playoff roster. For your 25th man, call up a specialty player like MikeT23 alluded to. A good example is a guy with 95 speed, who can be used strictly as a pinch runner, a defensive SS, or a 3rd catcher. Another example could be a LOOGY with 4 stamina who you would never use in the regular season due to his limited pitch counts, but he could be useful in a short series. Most people think you should up the pitchers pull rating too (like going from a 1 to 2 or 3), but I haven't made the playoffs enough times to experiment with that.