Here we go, I fixed it to run on 64bit Operating System.
Some instructions first... I copied and pasted the instructions, I didn't mess with any JP language settings on my computer and it seems intelligible as is-
You will probably have to play with the Japanese language settings on your computer.
Before installing the program, your Windows must be set to Japanese Language as default. Restart computer.
Extract the contents of FFXImodelviewer.zip.
The .lst files should be in Japanese text make sure your default language is set to Japanese
"FFXImodelviewer.zip must be extracted AFTER your language is set to Japanese. If you change the language settings after extraction, the model viewer will not be able to read the .lst files = only heads, missing armor, scrambled interface, or other errors."
1. Choose your model to be edited from the modelviewer.
2. Put a check mark infront of the 4th command under the droplist MQO(M) on top.
3. Then click at the export button and choose which part of the model you want to export.
4. If you want to only edit the textures, just edit the BMP file(s) in the same folder as your MQO file.
5. Use Metasequoia or other 3D programs that can read MQO files to edit the polygon.
6. Group the MQO, BMP, and MCD files of your model in the same folder.
7. Then use the first command under FILE(F) on the top left corner of the modelveiwer to convert the MCD file into DAT.
8. Replace the original file with the edited one.
*The modelveiwer shows the file location as ROM-FOLDER-FILENAME, e.g. 1-31-82 = ROM1-FOLDER31-FILE82.
**The name of the backup file created durning importing is the location of the file, e.g. 1031082 = ROM1-FOLDE31-FILE82.
This information was all found here-
and the 64 bit link is here -