Mods and CC packages don't show up in launcher. They only show up in game, and if you've got scripting mods, a window opens in main menu every time you start the game to warn that you've got scripting mods installed. It looks like this (click on thumbnail to enlarge) :
And after you've installed mods, don't forget to delete the 5 cache files (CASPartCache.package, compositorCache.package, scriptCache.package, simCompositorCache.package, socialCache.package) before restarting your game. Otherwise your new mods won't work as long as you haven't cleared cache.
If mods still don't work, download the resource.cfg file directly from NRaas because not all versions work perfectly, I got issues with one from another site.
http://nraas.wikispaces.com/file/detail/Resource.zipIf it still doesn't work, check that your mods and patch are compatible. Mods usually work for one specific patch and not for all versions. On Mac, if your game is up-to-date, it should be 1.67.