You configure the import/export rules at runtime, using a configuration form the modules provide for you. See the documentation in the appstore page for information on how to link these forms to your application and the available configuration options.
In Mendix there is built-in functionality for exporting data grids to Excel, simply add an 'Export to Excel' button to your grid to create export functionality. These modules extend this functionality with import capabilities, and more customization options for exports.