>I can put the calculator and diary in menus with _mst_calcu, _mst_diary; but I can't get them to work with sys(1500). What would be the menuname to use in the sys(1500) function, or isn't this possible?

The sys(1500) works for system menus only. You'll have to add "_mst_calcu" to one of system pads, for example

DEFINE BAR _mst_calcu OF _msystem PROMPT "Calculator..."
SYS(1500, "_mst_calcu", "_msystem")