In a small bowl, dissolve gelatin in boiling water. Stir in cold water. Cover and refrigerate until partially set. Fold in blueberries. Transfer to an 8x4-in. loaf pan coated with cooking spray. Cover and refrigerate for 1 hour or until set.
For topping, in a small bowl, beat the cream cheese and sour cream until smooth. Stir in the sugar substitute and vanilla. Unmold gelatin; cut into six slices. Top each slice with topping and pecans.