I think you can still use the code I show (beforeSubmit event).
In this method you could see :
var sr = jQuery(”#list”).getGridParam('selrow'); var rowData = jQuery(”#list”).getRowData(sr);
The first line take the current row selected and the second one get the data in this row. Now you can access any value in the row doing something like:
alert(rowData['id']);
Also there is a postData array that you can manipulta using the setPostData() and appendPostData() methods…