Haha found the solution myself:

$(“#customerSearchForm”).submit(function (e) {
e.preventDefault();
$('#customerResults').jqGrid().setGridParam({
url: $('form:first').attr('action'),
postData: $('form:first').serialize(),
datatype:'json',
jsonReader : { root: “rows”, page: “page”, total: “total”, }
}).trigger(“reloadGrid”, [{page:1} ]);
});