Drop this directory into
/Applications/iPhoto.app/Contents/PlugIns/HTMLExporter.iPhotoExporter/Contents/Resources/English.lproj/Templates/
If you are not using the English locale on your mac, you will have to put it under the appropriate "lproj" directory instead.
Once installed, you can use iPhoto's Export feature (Web tab) and select the fancyBox template from the dropdown.
BSD License.