ok... never mind... answered my own question (quick little google search).
Pitcher has to satisfy the following conditions:
1. The pitcher is the last pitcher in a game won by his team;
2. The pitcher is not the winning pitcher (for instance, if a starting pitcher throws a complete game win);
3. The pitcher fulfills at least one of the following three conditions:
1. He comes into the game with a lead of no more than three runs, and pitches at least one full inning.
2. He comes into the game with the potential tying run being either on base, at bat, or on deck. In other words, the potential tying run is either already on base or is one of the first two batters he faces.
3. He pitches at least three "effective" innings (this is the only subjective criterion and is judged by the official scorer).