Customize HRD

Hi all!

I need to customize the HRD message that appears by default in SharePoint 2013 when 2 authentication providers are selected for the same Web Application Zone.

I have searched on Internet wether if it's possible or not, but the only thing that I have found is how to customize the HRD for ADFS and not for SharePoint.

I want to put a message before the Sign In to explain to the users how they can use the HRD to authenticate.

Any suggestion would be appreciated

Thanks in advance