Do try to activate grid and use SendKeys Up/Down arrow,PageUp/Down as suggested by Venu.
You can always use MakeCellVisible to scroll to intended cell as below.
'Scroll to Display a Specified Cell in the View.
'The following example uses the MakeCellVisible method to scroll the cell located in the ninth row, third column of the "myDataGrid" table into the view.
SwfWindow("DataGrid Control Sample").SwfTable("myDataGrid").MakeCellVisible 8, 2