Modify Jira Login Page

We would like some kind of a UI mechanism to add custom text on the Jira Login page. For example we would like to be able to add language about what kind of credentials to use for the Jira login. I realize that can be done in the login gadget but not in the login screen. We get a lot of users asking what is there login credentials and it would be nice if they saw something on the onset telling them to try "xyz" for the username and password.