Add “tabindex” to checkbox field?

Nevermind, I managed to solve the issue.

I turned off “Enable default checkbox” and recreated it in “comment_form_default_fields” filter.

In case anyone else is looking for this solution, this is what I’ve done :

function my_comment_form_fields($args) {
$args['comments_notify'] = '<div class="comment-form-subscriptions">
	<input type="checkbox" name="subscribe-reloaded" id="subscribe-reloaded" tabindex="5" value="replies">
	<label for="subscribe-reloaded">Notify me of replies to my comment via e-mail.</label>
	</div>';
return $args;
}
add_filter('comment_form_default_fields', 'my_comment_form_fields');