@Erik got me on the right path on this one. His solution works, but preserves the existing pseudo-modal popup confirmation UI, which I wanted to avoid.
It also doesn't capitalize on the services the JqGrid ASP.NET component provides. The component actually takes care of all CRUD operations as long as it's wired up to a properly configured data source (ObjectDataSource, SqlDataSource, etc).
This missing piece for me was the mechanics behind the component's CRUD operations. By poking around with Fiddler I was able to see that it POSTs the relevant data to the same page, with the ClientID of the JqGrid object in the querystring:
MyPage.aspx?jqGridID=ctl00_ctl00_Content_Content_MyJqGrid
For deleting, the contents of the POST are as @Erik describes:
oper=del&id=18
So I've been able to duplicate the operation on my own so that I retain complete control of the whole process:
$(".DeleteButton", grid).click(function(e) {
var rowID = getRowID(this);
$(grid).setSelection(rowID, false);
if (confirm('Are you sure you want to delete this row?')) {
var url = window.location + '?jqGridID=' + grid[0].id;
var data = { oper: 'del', id: rowID };
$.post(url, data, function(data, textStatus, XMLHttpRequest) {
$(grid).trigger("reloadGrid");
});
} else {
$(grid).resetSelection();
} // if
}); // click
getRowID = function(el) {
return $(el).parents("tr").attr("id");
};