This is an example plugin that contains a function to set the CSV delimiter to tabs rather than CSV.

ee_custom_functions_plugin.php

<?php
/*
Plugin Name: Event Espresso Custom Functions Plugin
Description: Add custom functions for Event Espresso to this plugin.
/* Begin Adding Functions Below This Line; Do not include an opening PHP tag as this sample code already includes one! */

//This function sets EE to use tabs for the CSV delimiter.
function tw_ee_csv_tab_delimiter() {
    return "\t";
}
add_filter( 'FHEE__EE_CSV__fputcsv2__delimiter', 'tw_ee_csv_tab_delimiter' );