Question about logging food in MyFitnessPal

I have begin to use MyFitnessPal.com for food logging. I found it a good tool in keeping myself on track. However I have a question. Since I often find myself away from home and eating Lean Cusine or Health Choice Dinners. I always choose the ones with the most protein and never eat the pasta or rice.
How would they get logged? If I choose the the entire dinner " the calorie count is off and it can not be changed.
Any suggestions? Maybe there is another site that I could use that allows changes. I do not mind "doing the math" to delete the calories for the uneaten carbs.

 That is one drawback of MFP. But I think it has a feature to submit foods and their calorie counts, so maybe you can do the math then submit the food minus what you don't eat, so it pops up on their list of foods.

I would just put in that you ate 1/2 or 2/3 of the meal. It may be some calories and protein off, but at least it's something.

You can add your own meal..Call it lizpete's Lean Cusine. Just look on the box at how much protein there is in it and put just that amount is the description area, you will be given, when you create a custom meal. Also be sure to weigh the protein part on a scale and record that amount on the entry area. Then when you search for your dinner in the search section just enter the dinner you made up. Be sure and list it so that others if they know about it can use the meal you developed. I know these instructions are not very clear, but play with it and you will see what I am talking about. I have most of my breakfasts, and some dinners listed under Larry's so that I have just what I eat and not what someone else has done. Also there are a lot of mistakes in what others have put in the system so check them out if you can. MFP is very customizable and flexible. Also MFP has the best library of all and I have tried most of them. Best tool I have found to keep me on track, will never be without it as far as I am concerned. 

Don't do those meals but the way I am I would count it as like half or whatever even if it was the lower calorie portion. I typically err on the conservative side so I will typically be under caloric goal.

Thanks to all for responding. I will have to play around with it. Since I do not carry my scale with me. (added weight to the luggage and TSA is a PITA) I probably can eyeball it.