First off all you need a menu, when you got your menu: place on your Arma 2 OA folder (you need to know the ".sqf" file on your menu and the hot key to open the menu and etc) .
Now you will need a script executer (is one here on MPGH).
Now run the DayZ then open the script executer and type the ".sqf" file and execute.
Ingame pres the key to open the menu and it should work.
NOTE: If you are playing with battleye on you gonna need a bypass.