One other thing here...

While talking with Kevin about incorporating this into the framework docs, we discovered that my cut/paste skills aren't up to the task.

Both the second and third pieces of code were missing a cast to the appropriate subclass of ADefaultValues.

Second piece of code should have read as follows:

OrderDefaultValues ordDefaults = (OrderDefaultValues)this.OrderObj.DefaultValues;

//Here, we're storing the Product and Customer (selected by our users and stored as static fields) to which our new order belongs.
ordDefaults.ProductID = GlobalData.Product.GetProductID();
ordDefaults.CustID = GlobalData.Customer.GetCustomerID();

this.NewRow(ordDefaults);

This is "new look" 3rd section:

protected override void HookSetDefaultValues(DataRow dr)
{
OrderDefaultValues ordDefaults = (OrderDefaultValues)this.OrderObj.DefaultValues;

   dr["iProductID"] = ordDefaults.ProductID;
   dr["iCustID"] = ordDefaults.CustomerID;
}