Ciao, ho lo stesso problema.
Avevo già capito di dover inserire il codice in index.php del mio template, il problema è che quando lo inserisco la slider non si allinea correttamente al centro nonostante abbia provato anche ad utilizzare allign:"center".
Questo è il mio codice idenx.php, io avevo provato ad inserire la slider tra <?php get_header(); ?> e *<?php. *Come plugin ho utilizzato "WP Content Slider".

[HTML]<?php get_header(); ?>
<?php if(function_exists('wp_content_slider')) { wp_content_slider(); } ?>
<?php

if(get_option('boxof_home') == "movies") { ?>
<?php include (TEMPLATEPATH . '/lib/movie-home.php'); ?>
<?php } else { ?>

<div id="content">

<?php if (have_posts()) : ?>
<?php while (have_posts()) : the_post(); ?>

<div class="post" id="post-<?php the_ID(); ?>">
<div class="title">
<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2>
</div>
<div class="postmeta">
<span class="author">Posted by <?php the_author(); ?> </span> <span class="clock"> <?php the_time('M - j - Y'); ?></span> <span class="comm"><?php comments_popup_link('0 Comment', '1 Comment', '% Comments'); ?></span>
</div>
<div class="entry">

<?php
if ( has_post_thumbnail() ) { ?>
<img class="postimg" src="<?php bloginfo('stylesheet_directory'); ?>/timthumb.php?src=<?php get_image_url(); ?>&h=150&w=200&zc=1" alt="" />
<?php } else { ?>
<img class="postimg" src="<?php bloginfo('stylesheet_directory'); ?>/timthumb.php?src=<?php bloginfo('template_directory'); ?>/images/dummy.jpg&h=120&w=200&zc=1" alt="" />
<?php } ?>

<?php wpe_excerpt('wpe_excerptlength_index', ''); ?>

<div class="clear"></div>
</div>

<div class="singleinfo">
<span class="category">Categories: <?php the_category(', '); ?> </span>
</div>

</div>
<?php endwhile; ?>

<?php getpagenavi(); ?>

<?php else : ?>

<h1 class="title">Not Found</h1>
<p>Sorry, but you are looking for something that isn't here.</p>

<?php endif; ?>

</div>
<?php } ?>

<?php get_sidebar(); ?>
<?php get_footer(); ?>[/HTML]