Adding a new operator is quite complex, since you would have to create the correct file/folder structure for each and every GSX ground vehicle, and any update will remove all your changes.
But, assuming you figured it all out, the most important thing is to create some rules to assign the new operator to airports. Have a look at the rules_handling.cfg file in the Addon Manager\TEXTURE folder, the first lines are comments briefly explaining how rules work.
Since this file will also be overwritten with every update, it's best to create a custom rules_handling.cfg file, containing ONLY the rules for the new operator, to be placed in %APPDATA%\Virtuali\TEXTURE
And, after adding or changing any rule, you must clear the airport cache, by removing this folder
%PROGRAMDATA%\Virtuali\Couatl
Since also the rules and the models are cached there, so you won't see any changes unless you both have a new rule and clear the cache.
