If you're using the Modal Popup version, you'd need to make a minor edit to our files as we aren't using language strings for those 2 word. That will be fixed in the next release. To fix, edit the /modules/mod_sclogin/tmpl/login.php file and search for the words you're looking for on lines 13, 15, 19, and 21.
The Register page itself is a part of Joomla. You'd need to edit the com_users.ini language files to edit the text for those pages.
I hope that helps, but if you need anything else, just let me know.
Glad to help. Should you need anything else, just let us know.
Finally, if you haven't already, please consider leaving a rating and review for SCLogin, or our support, on the Joomla Extension Directory. It certainly isn't required, but is very appreciated:
http://extensions.joomla.org/extensions … tion/24054