gistfile1.php

add_filter( 'tribe-events-bar-filters',  'setup_my_field_in_bar', 1, 1 );

function setup_my_field_in_bar( $filters ) {
	$filters['tribe-bar-my-field'] = array( 
		'name' => 'tribe-bar-my-field',
		'caption' => 'My Field',
		'html' => '<input type="text" name="tribe-bar-my-field" id="tribe-bar-my-field">' 
	);

	return $filters;
}