I just finished 2 projects both with LCD scroll and keypads.My way may not be good enough,but I'm just offering some info.
I think it's simple to do that.First make sure there're variables defined corresponding to each number you want to display.And set high&low limits for all of them to make the value loop back when you reach the limits while scrolling.Next,group them,and list them in a certain sequence.Define as many pointers as necessary.E.g,pointer indicating position of the cursor,pointer signifying the current variable you are operating,etc.Then you will have to change the variable pointer as well as the the cursor pointer in the function (or subroutine) which processes the 'Scroll' keystroke.And you need to update the position of the cursor on the LCD corresponding to the cursor pointer's value.After this,you have to increment the variable designated by the variable pointer in the 'INCREMENT' keystroke's function and decrement it in the opposite one.Make sure the value loops back as I previously mentioned.I think you can figure out the rest.
Good luck!