To keep it most simple, I just copy traffic files over from FSX and modify them to my current whim using the ancient TTools utility by Lee Swordy. Sometimes the traffic.bgl must first be decompiled using AI Flight Planner, but after that I prefer a basic manual process. Never have gone for the huge traffic packages that fill the skies with planes. I like to have, for example, a few GA planes doing circuits or parked at smaller air fields or military bases and stationary (scenery) aircraft carriers. Lots of fun.