apply the error messages to custom login page

i was wondering if there is a way to show the plugin errors on custom login page, it would be nice if the developer will show how, if not, it would be nice to have that in the future, some sort of way to apply the messages into custom log-in page, since most of the sites these days using that custom log-in and try to avoid the wp-login page.
(and even hide it)
thanks
Ben