Put both the items and the custom characters mods into the MODS folder (do NOT put the items into the CustomCharacterData folder).
Launch the game.
Download any of the files and unzip it into the new folder named "CustomCharacterData".
To check that everything is correct you can go to the right side of the breach and check is the knight there.
Descriptions of what these items do can be found at the download page of the items.
NOTE: The Soul Vessel needs to be dropped and picked up again for it to work. There is no known fix for this at the moment. This bug was fixed in the recent patch of the items mod. Also be sure to re-download the newest version of the character for it to work.
@pavlov.andrei.d I felt like giving it a mouth, no real reason to it :)
And sorry for being inactive for the past few weeks.