Thanks for the feedback. Unfortunately, I don't have a N810 to test it with, and I'm really unfamiliar with how the hardware keyboard works. From your post, I'm guessing the holding Fn while pressing certain keys will change the function of those keys (changing some keys to numbers)? And double pressing Fn will turn Fn-lock on?
Changing the number of people can be done three ways: by entering the number into the box, by pressing the up/down buttons on the right of the box, or by pressing up and down on the d-pad while the box is active. Let me know if that works for you. Can you elaborate on how you couldn't change the number of people? Were you unable to select the box? Or once selected, were you just having keyboard trouble?