This class is an example of how to add rewrite rules and the actions to take should the rewrite be matched.

class-rewrite-rules.php

<?php
/**
* WP_Theme_Rewrites Class for WordPress.
*
*/

if(realpath(__FILE__) === realpath($_SERVER["SCRIPT_FILENAME"]))
	exit("Do not access this file directly.");

class WP_Theme_Rewrites {
	var $rewrites = array(
		'events/(upcoming-events)/?$' => 'index.php?post_type=event&the_scope=$matches[1]',
		'events/(past-events)/?$' => 'index.php?post_type=event&the_scope=$matches[1]',
	);

	function __construct(){
		add_action( 'wp_loaded', array(&$this, 'flush_rewrite_rules') );
		add_filter( 'rewrite_rules_array', array(&$this, 'insert_rewrite_rules') );
		add_filter( 'query_vars', array(&$this, 'add_query_vars') );

		add_action( 'pre_get_posts', array(&$this, 'filter_event_posts') );
		add_action( 'template_redirect', array(&$this, 'switch_template') ); 
	}
	
	/**
	 *
	 * Perform flush_rules() operation if our rules are not yet included.
	 *
	 * @return	void
	*/
	function flush_rewrite_rules() {
		$rules = get_option( 'rewrite_rules' );
		$rewrites = $this->rewrites;
		for( $i=0; $i<count($rewrites); $i++) {
			$key = key( $rewrites );
			if ( ! isset( $rules[$key] ) ) {
				global $wp_rewrite;
				$wp_rewrite->flush_rules();
				break;
			}
		}
	}

	/**
	 *
	 * Override rewrite rules.
	 *
	 * @return	array
	*/
	function insert_rewrite_rules( $rules ) {
		$rewrites = $this->rewrites;
		return $rewrites + $rules;
	}

	/**
	 *
	 * Add query variable to global in order to switch the template.
	 *
	 * @return	array
	*/
	function add_query_vars( $query_vars ) {
		$query_vars[] = 'the_scope';
		return $query_vars;
	}

	/**
	 *
	 * Switch template if custom route detected
	 *
	 * @return	void
	*/
	function switch_template() {
		$scope = get_query_var('the_scope');
		$template = locate_template("archive.php");
		if ( !empty($scope) && $template) {
			load_template($template);
			die;
		}
	}

	/**
	 *
	 * Filter event posts for custom query var
	 *
	 * @return	void
	*/
	function filter_event_posts( $query ) {
		if ( is_admin() ) return;
		$scope = get_query_var('the_scope');
	    if ( $query->is_main_query() && !empty($scope)) {
			$compare_operator = array_shift(explode("-",$scope)) == "upcoming" ? ">=" : "<=";
			$args = array(
				'posts_per_page' => -1,
				'post_type' => 'event',
				'meta_query' => array( 
					'key' => '_start_ts', 
					'value' => current_time('timestamp'), 
					'compare' => $compare_operator, 
					'type'=>'numeric' 
				),
				'orderby' => 'meta_value_num',
				'order' => 'ASC',
				'meta_key' => '_start_ts',
				'meta_value' => current_time('timestamp'),
				'meta_value_num' => current_time('timestamp'),
				'meta_compare' => $compare_operator,
			);
			foreach($args as $key => $val) {
				$query->set($key, $val);
			}
	    }
		if ( $query->is_search() ) {
			$query->set('post_type', array('news','video','paper','book','course','page','event'));
		}
	}

}
new WP_Theme_Rewrites();