Depends on what do you want to accomplish. XCOMModHelper is great tool to apply mods to the game (EU and EW). Every mod, that uses XCOMModHelper for deployment, has its configuration in xml file - that is what is written after -c option. There are 2 ways for you. Wait until are old mods updated for current version of XCOM Enemy Unknown (patch 6) or downgrade the game to patch 4 (already linked the thread). I bought XCOM EW and it's exciting (now on the 2nd playthrough). I just wanted to edit the DefaultGameCore.ini file myself and have it stick. Nothing major, just balance tweaks, mostly.