It took me awhile, but I finally figured out how to do this.1. Place the extracted dictionary files (Spanish English.SKContent, Spanish English.SKNoteHeader, & Spanish English.SKWrite) in your UserData directory (probably c:Program FilesStarfishTrueSync DesktopUserData).
2. Insert your Rex in the cradle or PC Card slot.
3. Run the TruSync Desktop program.
4. Click on the TrueSync icon on the right side of the screen.
5. Click on the little Memo icon at the top left of the screen or select "Memo" from the "Data" pull-down menu. This will bring up the "Memos Properties" page.
6. Click on "Refresh List" from the "Memos Properties" page.
7. The Spanish Dictionary will now be listed on the right side of this page and you may then select the Rex Pro category you want to assign it to.
Buena Suerte!