There's nothing wrong with forcing I/O, but I want my simulation act more like a real world system rather than poking around in PLC itself.I am not a GE user but most PLC programming software allow you to "force" an input on.
Ultimately I am going to end up writing a self contained, standalone, specialized HMI system that does exactly what I want it to do. Its a long story, but there are benefits and strategic advantages for me to do this.