How to setup custom export inside the project

1. Open your document definition inside Project Setup Station
2. Navigate to Document Definition > Export settings
3. Click "Add" Button and choose "Custom export (Script)" at Type
4. After click "Next" you can upload your script inside, using the "Edit script" button or do it later, using "Edit" button on Export settings window

You can find the documentation and examples using FlexiCapture help documentation inside the app (Help>Help topics, or press F1) and follow the next path, as you can see on the screenshot:

Alternatively, documentation can be found online: https://help.abbyy.com/en-us/flexicapture/12/distributed_administrator/scripting_export_ex