The Chinese word dictionary that ships with Chinese Toolbox is the CC-CEDICT dictionary from MDBG. The dictionary exists in the file cedict_ts.u8 which is installed in the Chinese Toolbox program directory.
You can download an updated version of this file from http://www.mdbg.net/chindict/chindict.php?page=cc-cedict and copy it to the Chinese Toolbox program folder, typically c:\\Program Files\Toolbox Coding\Chinese Toolbox.
You can edit this file directly, but a more convenient approach involves using the dictionary editing functionality of Chinese Toolbox. The word dictionary editing features of Chinese Toolbox are now quite robust, allowing you to edit, remove, add to, temporarily exclude, and revert changes to the word dictionary or word dictionary entries.
Word dictionary entries appear in the Word Dictionary window in the lower right of the default layout of the interface.