I forgot to mention. You can write a function similar to wp_login_form() in your functions.php and use that instead.
You can’t overwrite anything you want. Those hooks mentioned in the article are pre-defined and only allows modifications to certain parts of the code.
If you look at wp_login_form() in /wp-includes/general-template.php
/**
* Provides a simple login form for use anywhere within WordPress. By default, it echoes
* the HTML immediately. Pass array('echo'=>false) to return the string instead.
*
* @since 3.0.0
* @param array $args Configuration options to modify the form output
* @return Void, or string containing the form
*/
function wp_login_form( $args = array() ) {
$defaults = array( 'echo' => true,
'redirect' => site_url( $_SERVER['REQUEST_URI'] ), // Default redirect is back to the current page
'form_id' => 'loginform',
'label_username' => __( 'Username' ),
'label_password' => __( 'Password' ),
'label_remember' => __( 'Remember Me' ),
'label_log_in' => __( 'Log In' ),
'id_username' => 'user_login',
'id_password' => 'user_pass',
'id_remember' => 'rememberme',
'id_submit' => 'wp-submit',
'remember' => true,
'value_username' => '',
'value_remember' => false, // Set this to true to default the "Remember me" checkbox to checked
);
$args = wp_parse_args( $args, apply_filters( 'login_form_defaults', $defaults ) );
$form = '
<form name="' . $args['form_id'] . '" id="' . $args['form_id'] . '" action="' . site_url( 'wp-login.php', 'login' ) . '" method="post">
' . apply_filters( 'login_form_top', '' ) . '
<p class="login-username">
<label for="' . esc_attr( $args['id_username'] ) . '">' . esc_html( $args['label_username'] ) . '</label>
<input type="text" name="log" id="' . esc_attr( $args['id_username'] ) . '" class="input" value="' . esc_attr( $args['value_username'] ) . '" size="20" tabindex="10" />
</p>
<p class="login-password">
<label for="' . esc_attr( $args['id_password'] ) . '">' . esc_html( $args['label_password'] ) . '</label>
<input type="password" name="pwd" id="' . esc_attr( $args['id_password'] ) . '" class="input" value="" size="20" tabindex="20" />
</p>
' . apply_filters( 'login_form_middle', '' ) . '
' . ( $args['remember'] ? '<p class="login-remember"><label><input name="rememberme" type="checkbox" id="' . esc_attr( $args['id_remember'] ) . '" value="forever" tabindex="90"' . ( $args['value_remember'] ? ' checked="checked"' : '' ) . ' /> ' . esc_html( $args['label_remember'] ) . '</label></p>' : '' ) . '
<p class="login-submit">
<input type="submit" name="wp-submit" id="' . esc_attr( $args['id_submit'] ) . '" class="button-primary" value="' . esc_attr( $args['label_log_in'] ) . '" tabindex="100" />
<input type="hidden" name="redirect_to" value="' . esc_attr( $args['redirect'] ) . '" />
</p>
' . apply_filters( 'login_form_bottom', '' ) . '
</form>';
if ( $args['echo'] )
echo $form;
else
return $form;
}
there are only filter hooks that allows you to add codes in between the input fields.
