On the other hand, if you mean you want to create and insert your very own pilot, I don't know. But on my MSFS Steam
install, the folders with files for the various MSFS pilots you can select in Misc are located in the Official folder:
Official -> Steam -> asobo-simobjects-characters -> Simobjects -> Humans -> Pilot -> model.Pilot<pilot name>
These pilot files are not protected, at least on my Steam install, and can be changed. I don't know if you could add your
own model.Pilot folder, using the already existing ones as templates, and have it show up in the Misc pilot list for you
to select, and then have it show up in the plane when you load the flight.
Just a thought.
The reason I found this out is that I like to have an "invisible" pilot I can use when I don't want a pilot or co-pilot to show,
so I go in and remove the files from one of the model.Pilot folders. I like to use the model.Pilot_Female_Uniform_Indian
folder, which is the last pilot in the Misc list, Pilot#24. Of course I always do a backup in case I may ever need a female
uniformed Indian pilot or co-pilot.