Copy your game into the multiplayer save folder.
Start up a multiplayer session.
Create some silly character for the sole purpose of transfering goodies and put him into the party.
Load your game.
Give your "mule" character all the stuff you wish to transfer and export him.
Start your new single player game on the difficulty you want and save at the first opportunity.
Again, copy your savegame to multiplayer and start it up.
Import your mule and hand out all the goodies you like.
Save and copy the multiplayer save back to the single player save folder.
You're in business. Repeat a couple of times or use more mules if you wish to transfer more stuff.
Of course, you could import the same mule again and again and hand out the same goodie multiple times, but that would really be (gasp) cheating (as if it wasn't already, but who cares).
[url="http://www.sorcerers.net/Games/BG2/SpellsReference/Main.htm"]Baldur's Gate 2 Spells Reference[/url]: Strategy, tips, tricks, bugs, cheese and corrections to the manual.