Re-write rules on views

Hi all,
	The docs seem slim in this department.. what is the proper syntax for an 
update to a view with multiple tables?

Here's a view I'd like to update:

  CREATE VIEW "users_perms_view" AS
  	SELECT
  		 users.user_id,
		 users.username,
		 users.name_first,
		 users.name_last,
		 permissions.permission_name,
		 permissions.permission_description
  	FROM
  		 users,
		 users_permissions,
		 permissions
  	WHERE
  		 ((users_permissions.user_id = users.user_id) AND
		 (users_permissions.permission_id = permissions.permission_id));

This rule works fine as far as it goes:

CREATE RULE "update_users_perms_view" AS
	ON UPDATE TO users_perms_view DO INSTEAD
	UPDATE
		users SET
  		username = NEW.username,
		password = NEW.password,
		name_first = NEW.name_first,
		name_last = NEW.name_last,
		active = NEW.active,
	WHERE
		user_id = OLD.user_id;

How do I update the  users_permissions and  permissions table?

Thanx,