Unfortunately, you can't. The SCLogin module is just that.. a module. When an extension tries to redirect a user, it goes to the Joomla User Component's login page. The only thing you could do is:
* Setup a redirect from the standard Joomla login page to a custom article or other page
* On that custom page, set the SCLogin module to display
That could work, but it wouldn't force the SCLogin module to popup on whichever page requested the login view, as I think is what you're looking for.
I hope that helps explain,
Alex
Configure default Joomla Login screen to default to SClogin?
