For anyone trying to get zdoom, or presumably any source port, working in launchbox .
The way I did it was to add 2 new platforms, one for doom and one for doom 2 in launchbox
see picture (I,ve only done doom II)
Put all of your addons ie textures, sprites, sounds, lights, skies etc into a folder called skins in the root folder of your zdoom exe, you want these to be files that are used universally every time you launch zdoom. So that all you will need to add is whatever pwad you want to load which we will have launchbox doing FOR us.
see picture
set up zdoom as an emulator and set it to scrape as md-dos tools > manage > emulators > add
see screenshot, and go ahead and set it as the default emulator for our doom or doom II platform
now all we have to do is find whatever iwads and pwads that we want to play and drag them indo launchbox as rom files with doom as our platform and zdoom as our emulator.
you'll have to find your own media as everything but doom, doom II, tnt, plutionia and the master levels won't scrape