[qualiteam]

The regular async script looks like this:

<script type="text/javascript">

  var _gaq = _gaq || [];
  _gaq.push(['_setAccount', 'UA-XXXXX-X']);
  _gaq.push(['_trackPageview']);

  (function() {
    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
  })();

</script>

I suppose you use 4.0.x, thus in skin1/customer/home.tpl before the Google tracking code appears, add this:

{if $main eq "search"}
  {assign var="searchterms" value=$search_prefilled.substring|escape};
{/if}

Change the tracking code like this:

<script type="text/javascript">

  searchterms = '{$searchterms}'.toLowerCase().replace(/\s/g,'+');

  var _gaq = _gaq || [];
  _gaq.push(['_setAccount', 'UA-XXXXX-X']);
  if (searchterms) {
    _gaq.push(['_trackPageview', '/search?q='+searchterms]);
  }
  else {
    _gaq.push(['_trackPageview']);
  }

  (function() {
    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
  })();

</script>