With the MessExtra interface (namely S.BOARD) you can combine Ctrl key (from keyboard) + RESET push-button
This sets up the starting position with white pieces up (RESET without Ctrl key places the white pieces down).
Ctrl is also useful with push-sensitive emulated chessboards to move pieces without having the chess computer registering it. Of course it is useless with auto-sensory boards because the chess computer detects the move anyway.