X3: Terran Conflict
The script will add commands "Save Weapon Loadout 1-4" and "Load Weapon Loadout 1-4" to the Interface section (under Extensions) in the Control menu. You then have to bind any keys you want to those commands and they will allow you to quickly switch weapon loadouts between different weapon configurations you have onboard your ship.
Note: this is my first X script ever, so I don't guarantee anything (as much as I've tested it myself it works; any remarks as to bugs / stuff I shouldn't have done / done otherwise in the script are welcome).
Forum members reported this didn't work terribly well. The uninstall script can be found here.