How to change datawindow data source from SQL to SP?

Suppose I have a datawindow which get data from direct SQL like:

select c1, c2,c3, ... from mytab where c1=:param

Then I create a new SP which return result dataset same as data in mytab.

Then I want to change this datawindow datasource to the new SP, but keep everything same(format, appearance, font, ...).

How I can do it without create new datawindow from scratch?