I've created entries called "estimated calories" "estimated fat" etc. You just add it as if you're adding any other user-entered food, with the "add food not listed" under the Search button on your nutrition tracker. You can enter a "food" called "calorie" and make the entry for 1 calorie (ignore the other nutrients), then when you go to add what your totals are, just add that many "servings" of "calories" to your tracker.
So if your total comes out to, say, 1,235 calories for the day, enter 1,235 servings of calorie to your tracker, and that'll reflect what you've had that day. You can do this for any of the nutrients you want to track. :)