One is found on level one, east sector (across from where you first enter the Severed Hand.
Another is found in the Sheverash tower on the lady elf (Kaylessa?) guarding the tower (after you finish clearing the tower, she asks you to kill her, and after doing so, you find the piece on her).
Another is found in the Solonar tower (the Priest tower) in a chest on the third level.
The final piece is found in the Corellon tower on the second level. I forget where, but it may be on a body or in a stash.
Hope this helps.
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Patience, my BUTT...I'm going to KILL something!!!