Thanks to tk102's helpful comment in http://lucasforums.com/showthread.php?t=162427
, I was finally able to get Kotor Tool (v1.0.2210.16738) to recognize my installation.
I have the Mac OS X Universal Binary (Intel) version of SW:KOTOR and I use Parallels (a virtual machine) to run Windows XP for Kotor Tool.
Unfortunately, Kotor Tool was unable to find my Kotor I installation even after I set its Path Manager to point to the top level of my SW:KOTOR directory tree.
The fix was to add the registry path helpfully provided by tk102:
1. Run regedit
2. Create nested keys (folders) "Bioware", "SW", and "KOTOR"
3. Create a String value in the KOTOR key (folder), called "Path"
4. Set the Path value to the path of the SW:KOTOR directory
After adding this path, Kotor Tool is able to find the data files.