Open Shadowkeeper and load a savegame. Go to the character to whim you wish to give the item by using the slider bar under the portraits. Then select Inventory, and for position select inventory as well. Then press "Change Item". The item list will now appear and you can select which item you want to place in the inventory slot. For example, if you want the robe of Vecna, go to Armour and select the robe. Then press the "assign to (charname)" button. You can also place the robe directly in the armour slot by selecting Body instead of Inventory.
The assign button may be hidden below the screen, so you should maximize your shadowkeeper window or drag the item browser upward.
As for the CLUAConsole:CreateItem codes, use the codes behind the items in the item browser (in the case of the Robe of Vecna it is WA2ROBE)
Then type the following sentence: CLUAConsole:CreateItem
"WA2ROBE") and press enter. Making typo's will cause active stack messages.
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The last arrow of Legolas kindled in the air as it flew,
and plunged burning into the heart of a great wolf-chieftain.
All the others fled. -J.R.R. Tolkien, The Lord of the Rings