$importResult = PodioImporter::process_app( $uploadResult->file_id, (int)$appJob->appId, array(
    "app_id" => (int)$appJob->appId,
    "mappings" => array(
        array(
            "field_id" => $fieldId,
            "unique" => TRUE,//True of the values for the field is unique, false otherwise,
            "value" => array(
                    "value_column_id" => //The id of the column to map to the value,
                    //"currency_column_id" => ,//The id of the column to map to the currency, if any,
                    //"currency_default" => //The default currency, if any
            )
        )
    )
) );