You can refer this link, and bind on some button click event.

http://stackoverflow.com/a/7298901/385377

Replace:
var grid = $("#grid").jqGrid({…}); with your grid id,
e.g.
var grid = $("#list1");

Abu, could you create example? Thanks.

Thanks Abu,

Unfortunately I could not get it working.
To test it I also updated your master-detail.php demo with the below code.
http://websalesdesign.com/proj/lib/phpgrid-full/index.php
The code below is the same as the stackoverflow except the list1 change.

<input type="button" value="Next" id="btnNext">

<script>
$('#btnNext').click(function () {

var grid = $("#list1").jqGrid({…});

var selectedRow = grid.getGridParam('selrow');
if (selectedRow == null) return;

var ids = grid.getDataIDs();
var index = grid.getInd(selectedRow);

if (ids.length < 2) return;
index++;
if (index > ids.length)
index = 1;
grid.setSelection(ids[index – 1], true);

});
</script>

Regards,
Glenn

My bad.
I took another look right after I sent the email.
Changed the line like you said and it works like a charm.
var grid = $("#list1").jqGrid();

Thank You Abu!