This is a very simple process showing how to edit the maps shipped with the game.
1. Make a new map. For example purposes, this map will be called ABC and the shipped map used will be Kamino (KAM).
2. Go to …\BF2_ModTools\data_ABC\Worlds\ABC and delete the world1 folder.
3. Go to …\BF2_ModTools\assets\worlds\KAM and copy all the contained folders; they should be: effects, msh, odf, and world1.
4. Paste those folders to: …\BF2_ModTools\data_ABC\Worlds\ABC.
5. Go to …\BF2_ModTools\assets\scripts\kam and copy the contents of the scripts that correspond to the game modes of the newly created map. Paste the copied contents into the corresponding files (in …\BF2_ModTools\data_ABC\Common\scripts\ABC), deleting the old contents (ex. KAM1c_con.lua -> ABCc_con.lua). (Alternatively, copy the scripts from KAM, paste them alongside the scripts for ABC, delete the corresponding scripts and rename the KAM scripts to match the old names.)
6. In each of the new .lua scripts go to the line where it loads the world:
and change it to:
7. The process is now complete. When editing the world with Zeroeditor, open kamino.wld from …\BF2_ModTools\data_ABC\Worlds\ABC\world1.