If you do not know how to insert these items into the game here is what you must do.
First, go to TeamBG And Download their Item Text Maker. Once you have downloaded that, run it.
Unzip the zip file you downloaded from me, and then in the text maker select IMPORT ITEM AND TEXT.
Select where you put the .tbg file. Once thats imported, it makes the .itm file.

Skip this if step if you have already done it. Open Baldur.ini in your Baldur's Gate directory in Notepad or other text editor.
Under [Game Options] add the following:
Cheats=1
Then save the file and run the game.
Now when you run the game, if you hit tab and ctrl at the same time, the Console will come up.
If you put the .itm file you exported earlier into the OVERRIDE folder, you will need to know the .itm's name.
If you wished to put a item file called pet.itm into the game, you would type this. CLUAConsole:CreateItem("pet") and it would create the item in the Leaders inventory.
Simple! If you would like more information on this, check out the full Cheats list on TeamBG's site.