[Edited by sawyer96, 12/1/2011 10:33:11 PM]
to change the path that the editor uses to find the save games you need to open the editor, right click on The Sith Lords, and select Change Path for The Sith Lords. from there select My Computer > Local Disk C:\ > Program Files(x86) > Steam > SteamApps > common > Knights of the Old Republic II.
give the editor a minute to load up the savegame(s) and proceed to edit the save(s)
Unfortunately, once you close the editor, it will not save the path to the steam KOTOR2 directory and instead revert to the default directory again...this means every time you want to edit a save you will have to direct the editor to steam's KOTOR2 directory.