wp_ajax_autocomplete_user and include_blog_users

So I am working on editing a messaging plugin and am trying to make it so when you type who the message is to it uses the autocomplete like how it is for super admins in multisite (this is on a multisite install) and I am trying to figure out how I implement wp_enqueue_script( ‘user-suggest’ ); into the following forum/messenger

<h2><?php _e('New Message', 'messaging') ?></h2>
				<form name="new_message" method="POST" action="admin.php?page=messaging_new&action=process">
					<table class="form-table">
					<tr valign="top">
					<th scope="row"><?php _e('To (usernames)', 'messaging') ?></th>
                    <?php
					$message_to = isset($_POST['message_to']) ? sanitize_text_field($_POST['message_to']) : '';
					if ( empty( $message_to ) ) {
						$message_to = isset($_GET['message_to']) ? sanitize_text_field($_GET['message_to']) : '';
					}
					?>
					<td><input type="text" name="message_to" id="message_to" style="width: 95%" tabindex='1' maxlength="200" value="<?php echo $message_to; ?>" />
					<br />

It is for the message to