I don't have Master Cook or an online subscription to the Weight Watchers recipe builder, so I do it the low-tech way. Specifically, I figure out the total number of points for the entire quantity made, then I figure out how many servings there are and divide the points by the number of servings to get a points value.
For example, I just made a big batch of soup. As I made it, I figured out the points for the individual ingredients and then got a points total for the whole pot of soup. Then, before I ate ANY of it, I figured out how many portions there were in the entire pot. I generally use 1/2 cup portions for soup, but it doesn't really matter what you use. You just have to pick an amount and find out how many are in the entire dish you've made. My pot of soup had sixteen 1/2 cup portions, so I divided the number of points for the entire pot (which happened in this case to be 16, too) by the number of portions (16 in this case) and got a points number for a serving (1 point per 1/2 cup serving).