The only important thing is that the action of your form should point to Elxis's index.php file.
<form name="mplampla" method="POST" action="xxxxxxxx">
<title>login page for BEC</title><table cellpadding="0" cellspacing="0" class="moduletable"> <tr> <td> <form action="http://www.something/login.html" method="post" name="login" > <table width="100%" border="0" cellspacing="0" cellpadding="0" align="center"> <tr> <td> Username <br /> <input name="username" type="text" class="inputbox" size="10" /> <br /> Password <br /> <input type="password" name="passwd" class="inputbox" size="10" /> <br /> <input type="checkbox" name="remember" class="inputbox" value="yes" /> Remember me <br /> <input type="hidden" name="option" value="login" /> <input type="submit" name="Submit" class="button" value="Login" /> </td> </tr> <tr> <td> <a href="index.php?option=com_registration&task=lostPassword"> Password Reminder </a> </td> </tr> <tr> <td> No account yet? <a href="index.php?option=com_registration&task=register"> Create one </a> </td> </tr> </table>