Custom error message at failed login

[Christopher Jazinski, modificado hace 6 años.]

I would like to be able to modify the HTML that is produced when a user fails a login (due to username/password). I have noticed that some people explain on how do to this using a hook and modifying the language.properties file; however this doesn't seem like its going to let me create a link. Basically what I want to happen is for the user to login with a bad user/password and then provide them with a link to an external resource that will walk them through resetting their passwords for the LDAP accounts. Is this still achievable by a hook? I've not written any hooks; could you point me in the right direction to get started. As always thanks for all the feedback and assistance.