Search Box for Wordpress Ecommerce?

I'm using the wordpress ecommerce plugin, and need to set up a search box on my home page (using code in a post). How do I make this code search only ISBN numbers? I'd like it so the customer can add several ISBN numbers to this one box. Thanks





%26lt;form id="search" method="get" onsubmit="return submitSearch();" %26gt;%26lt;input id="search_by" name="search_by" type="text" onfocus="if


(this.value==this.defaultValue) this.value='';" value="Enter ISBN Number Here" size="60"%26gt;%26lt;input src="http://www.123.com/wp-content/theme鈥?class="search-submit" id="search_submit" border="0" type="image"%26gt; %26lt;/form%26gt;|||You can add a hidden field that tells the search results to limit the search parameters to that ISBN field. You can insert that as a hidden field in the form, like this:





%26lt;input type="hidden" name="search_field" value="ISBN" /%26gt;





Note: you will need to confirm the name/value combination based on the advanced search parameters for the wordpress ecommerce search.