No problem. Other emulators have configs for setting up in GameEx but as far as having MAME integration, then MAME, Model 2, and ZiNc emulators are what's included. There are ways of using other emulators as well to launch certain roms with a different emulator based on the MAME list but the ones mentioned are in code. It's a good place to start off with and then go off of NonMAME's suggestions to have a more complete working system.