run time parameters in custom menu.

Hi All  can I give runtime parameters when clicking custom menu. ie. inputs given by users at the time of executing menu.

for example.

can i incorporate below plsql block as custom menu.

DECLARE
  num1 NUMBER := &num1;
  num2 NUMBER := &num2;
  result NUMBER;
BEGIN
  result := num1 + num2;
  DBMS_OUTPUT.PUT_LINE('The sum of ' || num1 || ' and ' || num2 || ' is ' || result);
END;
/

Thanks in advance.

Hari