Add login / logout links to any menu and position it

functions.php

<?php
/**
 * Add login / logout links to any menu and position it
 * Based On : http://www.viper007bond.com/2011/09/20/code-snippet-add-a-link-to-latest-post-to-wordpress-nav-menu/
 * 
 * Instructions : 
 * 1 - Add this code to your theme functions file
 * 2 - create a new custom menu item : http://cl.ly/image/092k303O3C2z DO NOT change this #loginlogout
 * 3 - Position the menu item where ever you would like it to appear : http://cl.ly/image/0p00131v1L09
 **/

// Front end only, don't hack on the settings page
if ( ! is_admin() ) {
    // Hook in early to modify the menu
    // This is before the CSS "selected" classes are calculated
    add_filter( 'wp_get_nav_menu_items', 'replace_placeholder_nav_menu_item_with_latest_product', 10, 3 );
}
 
// Replaces a custom URL placeholder with the URL to the latest product
function replace_placeholder_nav_menu_item_with_latest_product( $items, $menu, $args ) {
 
    // Loop through the menu items looking for placeholder(s)
    foreach ( $items as $item ) {
 
        // Is this the placeholder we're looking for?
        if ( '#loginlogout' != $item->url )
            continue;
 
	if ( is_user_logged_in() ):
		$outputurl   = wp_logout_url( home_url() );
		$outputtitle = 'Logout';
	else :
		$outputurl   = get_permalink( woocommerce_get_page_id('myaccount') );
		$outputtitle = 'Login';
	endif;
 
        // Replace the placeholder with the real URL / Title
	$item->url   = $outputurl;
	$item->title = $outputtitle;
    }
 
    // Return the modified (or maybe unmodified) menu items array
    return $items;
}
?>