Actually the code already is in the sim and in use with the P-51D. Example:
{ CLSID = "{DT75GAL}",connector = "PYLON_4_B",arg = 308,arg_value = 0.5 , forbidden = {{station = 5, loadout = {"{HVAR}"}}}},
Pylon 4 75gal droptank loadout, when selected forbids the HVAR rocket to be loaded onto station 5. Pretty simple actually.