For a project I needed to find a way to pull out more than one image per product in list.phtml (category page) but also pulling out a certain size , the below code allows you to load all the images for that specific product, you can then manipulate the image either adding classes to it or adding inline styles.

//get images for product
$product = Mage::getModel('catalog/product')->load($_product->getId());
$helper = Mage::Helper('catalog/image');
foreach ($product->getMediaGalleryImages() as $image) {
    echo "<img src='" . $this->helper('catalog/image')->init($this->getProduct(), 'thumbnail', $image->getFile())->resize(243) . "' />";
}
?>