The only ways to accomplish that are Simconnect or FSUIPC, being this last one the only possible if you need to make it work in both FS9 and FSX. And I guess you are aware that programming an FSUIPC interface is by no means an easy task.
Do you know how to load/unload weights (baggage and passengers) or fuel over a specified time (loading rate)? Are you familiar with those kind of gauges? I don't want to use simconnect, but something that works in FS9 and FS10. I presume it would be FSUIPC but I am not familiar with that kind of programming!