A common form of altering mods in XCOM is through the INI files, which can (and I recommend) be opened in a Notepad format to allow the editing of certain code that the modder has provided, here is a rough example of what to change to enable certain things for Utility Slot Sidearms WOTC

First go to your Steam/Steamapps/Workshop/Content/268500 folder, then find folder "1194081262"

Then go into the "Config" Folder, and select "XComUtilitySlotSidearms_WOTC.ini" and open it, which should open the document in a Notepad format.

Then you simply change variables from "true" to "false" or the other way around and vice versa, here is an example.

You want to enable Gremlins for your Utility Slot as a Sidearm, here is how to do it. Find the code "bEnableGremlins=false", this line can be found at the top of the INI file.

Now simply edit the line, so it says, "bEnableGremlins=true", this means that the Gremlins will be enabled as a Sidearm Utility, where the mod originally disabled it, now you have edited it to enable it.