The ical feed you add in calendar is saved via ajax.

The js code is at ajaxcalls_add.js at line 631

$('#edit_calendar').click(function () {......

The php code is at line 505 in ajax_functions_edit.php , function wpestate_ajax_update_ical_feed() .

The function that does the actual import is wpestate_import_calendar_feed_listing($edit_id); and can be found in icalendar.php file at line 3.

The cron job that checks for new feed data is in events.php at line 28.