Re-using WordPress session outside of WordPress

I’m wondering if there’s a way to re-use WordPress for session management outside of WordPress itself — the same way you could with PHPBB by including this little snippet of code:

<?php
	define('IN_PHPBB', true);
	$phpbb_root_path = '../phpbb/';
	include($phpbb_root_path . 'extension.inc');
	include($phpbb_root_path . 'common.'.$phpEx);

	$userdata = session_pagestart($user_ip, PAGE_INDEX);
	init_userprefs($userdata);
?>

I’ve looked round the forums for a while now but haven’t found any mention of a similar trick, I’ve long dumped the phpBB forum itself, but have had to keep it around as the rest of the site uses it for session management — would love to bring that function over to WordPress if at all possible.