I tried this to make cell non editable as per condition but don't know where to place this code, in $( document ).ready(function() or in onSelectRow : function(rowid, status, e) and what are the meanings of the parameters passed to that function? I'm newbie in Jquery. Let me know if you want to see my code for the same. Cheers!!!
If you would use free jqGrid then the solution would be very easy. One can specify function as the value of editable property. So you can specify callback function which inform jqGrid which cells of the columns will be editable and which not. See the article for details.