Page up and down without using keyboard

can any body tell me, how can I write the code for page up and page down in alv grid report without using keyboard.I have make a report(showing in alv grid formate) and I am using menu printer(se41) and gave P,P+,P-,P-- in function key.

and call this function in report using pf-status. but i didnot get the result without keyboard.while using keyboard page up and page down it is working fine.