This is some sample code that allows you to install Intercom via your child theme's functions.php file without the plugin.

functions.php

<?php
global $wp;
function is_page_to_exclude(){
  /* Replace these examples with any pages where you'd like the messenger to be hidden */
  $urls_to_exclude = array(
    "http://example.com/page-one",
    "http://example.com/page-two",
    "http://example.com/page-three"
    );
  $url_to_check = home_url(add_query_arg(array(),$wp->request));
  if (in_array($url_to_check, $urls_to_exclude)) {
		echo "TRUE";
  }
};
function intercom_script_footer(){ 
  if ( is_user_logged_in() ) { 
    $current_user = wp_get_current_user(); ?>

<script>
   /* Replace 'APP_ID' with your app ID */
    window.intercomSettings = {
    app_id: 'APP_ID',
    email: '<?php echo $current_user->user_email; ?>',
    user_id: '<?php echo $current_user->ID; ?>', 
    name: '<?php echo $current_user->display_name; ?>',
    created_at: <?php echo strtotime(get_userdata($current_user->ID)->user_registered); ?>,
    hide_default_launcher: <?php is_page_to_exclude(); ?>
};

<?php } else { ?>

<script>
   /* Replace 'APP_ID' with your app ID */
    window.intercomSettings = {
    app_id: 'APP_ID',
    hide_default_launcher: <?php is_page_to_exclude(); ?>
};

<?php } ?>

/*Replace 'APP_ID' with your app ID */
   (function(){var w=window;var ic=w.Intercom;if(typeof ic==="function")    {ic('reattach_activator');ic('update',intercomSettings);}else{var    d=document;var i=function(){i.c(arguments)};i.q=[];i.c=function(args)   {i.q.push(args)};w.Intercom=i;function l(){var   s=d.createElement('script');s.type='text/javascript';s.async=true;s.src='https://widget.intercom.io/widget/APP_ID';var x=d.getElementsByTagName('script')   [0];x.parentNode.insertBefore(s,x);}if(w.attachEvent)   {w.attachEvent('onload',l);}else{w.addEventListener('load',l,false);}}})()
</script>

<?php }
// To add intercom to the front end of your wordpress site:
add_action('wp_footer', 'intercom_script_footer'); 
//To add intercom to the admin area of your wordpress site:
add_action( 'admin_enqueue_scripts', 'intercom_script_footer' );
?>

Anyone been able to get user_hash to work? This code is great and works but can't get identity verification to work properly.