Problem with ALV Grid Control

We are using an ALV Grid display and downloading the output to a Spread Sheet. When we are downloading the output to Pivot table it is showing the sums of all numeric fields with

column name starts with 'Sum of <Field Name>'. But we need only sum of few columns. Is it possible? If so, how?

Also we need the sort sequence of our Grid Display to be considered while downloading to pivot table. Is it possible?

Let us know if any one worked with such scenarios