I am not sure I follow correctly, but you can only change what data is already being sent to kACARS.
You are limited to what kACARS can already display within its fields.
For example, when I modified how my schedules work, I modified the kACARS_Free.php file to send different data then it actually would with stock schedules - it sends the chosen a/c from the aircraft column in the bids table instead the one in the schedules. I also modified what you get when you click Get Aircraft.
All interaction is done from that file.
If you be more specific with what you need I can help out.