There is no easy way to do this.
You could create a helper object where the user can enter the amount. If you set this amount, trigger a data source microflow that retrieves the data with the limit filled from the helper object.
Again, this isn't a nice solution, but it should work.
// Get the list view widget var listView = dijit.byId("ListView1"); // Set the page size to 20 listView.setPageSize(20);