i guess i got you the right way.....u actually can open the config.php of your theme folder '/theme/yourtheme/config.php open it and search for the login u might find something like this...
'login' => array(
'file' => 'general.php',
'regions' => array(),
'options' => array('langmenu'=>false),
),
make a file named login.php in the theme/yourtheme/layout/login.php
copy the contenyts of the general.php to the above login.pnp and then make changes to it
if you want changes to be made to the styling and ui of the form u can change /login/index_form.html
hope this helps!!