If you have questions about using mojoPortal, you can post them here.
You may want to first review our site administration documentation to see if your question is answered there.
Is there a way to add custom text to the log-in page, in a similar way as we can on the registration page? I've had a skim through the forums and the messagetemplate filenames but couldn't find anything. Apologies if I missed it..
No, there is no customization built into the login page. Others have done it in the past by replacing the login page with their own custom one.