Aquí os dejo el código del Slider por si alguien puede darme pistas, muchas gracias!!
Código PHP:
<?php
$featured_data = vpt_elastislide_featured();
if (count($featured_data['big_thumb']) > 0 && is_array($featured_data['big_thumb'])) {
?>
<!-- Elastislide -->
<div class="gallery">
<div class="image-preview">
<div class="slide-vignette">
<div class="slider_cap">
<a id="slider_url" href="">
<h1 id="slider_title"></h1>
</a>
<span id="slider_desc"></span>
</div>
</div>
<?php foreach ($featured_data['big_thumb'] as $big_thumb_src => $key) { ?>
<img class="img_big <?php echo $big_thumb_src;?>" src="<?php echo $key; ?>" />
<?php } ?>
</div>
<!-- Carousel -->
<ul id="carousel" class="elastislide-list">
<?php foreach ($featured_data['small_thumb'] as $featured_post => $key) { ?>
<?php $image_url = $key != "" ? $key : get_template_directory_uri()."/images/slider-default.png"; ?>
<?php $src = $featured_data['big_thumb'][$featured_post]; ?>
<li data-id="<?php echo $featured_post; ?>">
<span class="url"><?php echo get_permalink($featured_post); ?></span>
<span class="desc"><?php echo $featured_data['excerpt'][$featured_post]; ?></span>
<a href="#">
<img src="<?php echo $image_url; ?>"/>
<span class="title"><?php echo $featured_data['title'][$featured_post]; ?></span>
</a>
<div class="thumb_title clearfix"><?php echo $featured_data['thumb_title'][$featured_post]; ?></div>
</li>
<?php } ?>
</ul>
<!-- End Carousel -->
</div>
<!-- End Elastislide -->
<?php } else { _e('Please select featured post to show the slideshow</br></br>','framework'); } ?>