Kneeling Press Ups

Why not just use the "push ups" entry? I can't image the burn would be significant. If you want to actually see "press ups" in your log, then you could just define a custom exercise with the same burn as a push up...

Do you mean modified push ups on your knees? (Not trying to be picky, just trying to understand the exercise you are talking about). I haven't seen that in MFP and would just put as a push up but make a note that you modified it (then you can show to yourself when you have progressed to other styles of pushups!). With push ups, you lose less than half a calorie per kg body weight per push up. I imagine modified is slightly less than that but not so much as to separate the exercise. They still suck when you do a bunch in a row!