These should be used in the header.tpl and can be changed to make code run on specific pages.

Run code only on the homepage

1.

{if $page_name == 'index'}
    <div class="home">
{else}
    <div>
{/if}

2.

{if $page_name == 'index'}
<script type="text/javascript">
    var yiw_prettyphoto_style = 'pp_default';
</script>
{else}
{/if}