jQuery Grid Plugin - jqGrid

I've succeeded in adding advanced search to my grid using this:

jQuery("#grid").jqGrid('navGrid',

"#pager",

{"edit":false,"add":false,"del":false,"search":true,"refresh":true},

{}, // default settings for edit

{}, // default settings for add

{}, // delete instead that del:false we need this

{"multipleSearch":true,"closeOnEscape":true,"closeAfterSearch":true}, // search options

{} // view parameters

);

I have an external form field that I would like to use to pass a filter object to and trigger a search on the advanced search object. I can't find any documentation on this.

The search plugin author shows the following but I can't seem to identify the proper selector to make this work:

jQuery("#filterTool").reset().add().search();

As you can see, using the demo code for adding the advanced search (top) there is no indication of what the ID is for the filter object. 

Can anyone help?