SASL EXTERNAL AUTH using client's SSL certificates

So is there any way to authenticate the clients by verifying the SSL certificate supplied by the clients , something on the lines of

http://xmpp.org/extensions/xep-0178.html

Also the example authentication scripts https://www.ejabberd.im/files/doc/dev.html#htoc9 , prompts for user name and password . Can this be enhanced in anyway to verify using the client's SSL certificate?