You can find the Stat files in Data\Editor\Templates\Stats\Shared now (since Larian added them a few days ago). Four your purpose it's viable to take the character.txt file you can find in ...\Shared\Generated\Data and copy it to Data\Public\Shared\Stats\Generated\Data (if there are no folders yet: create them). Now open the file with a text editor and search for the companions you want to edit. To know what information you can add/change have a look at the other characters in the file or have a look into the character.xlsm file you can find in the Editor Templates folder (s. above).
For Companion skills, as Sniper said, use the SkillSet file: you can find the .txt file in ...\Templates\Stats\Shared\Generated. (You can do this with the xlsm files and generating the text files via All.xlsm too, as Sniper described).

Edit: The Editor for EE should be available under tools in Steam. But for your purposes you don't need it.
You can make your mod selectable in the game menu this way (as Sniper described) so you don't have to delete the files to uninstall your mod.

Last edited by Abraxas*; 03/04/16 10:04 AM.

My mods for DOS 1 EE: FasterAnimations - QuietDay - Samaritan