Hi,
It's pretty simple using the OPT. I just saw your post and checked to see if a good assortment of aircraft were included by default and there are. I took a snip:

Once you've added as many aircraft as you like, while still using the OPT choose save and an XML file will be created. It's then necessary to create a BGL file and either copy the file to the Addon Scenery folder or a folder of your choice and add to the Scenery Library.
Jim F.