Hi all.
by the requests of people...
I show how it done on my local server (with my folder paths), replace it with yours.
1. Find your desirable sound and convert it to OGG format - in my example it is signalka.OGG. Place this file in to MPMission folder : D:\SteamGamesLibrary\SteamApps\common\arma 2 operation arrowhead\MPMissions\DayZ_Epoch_24.Napf\signalka.ogg
2. add to D:\SteamGamesLibrary\SteamApps\common\arma 2 operation arrowhead\MPMissions\DayZ_Epoch_24.Napf\description.ext reference to new sound file : http://pastebin.com/P1FYvLjy
3. Almost all of you use scripts like selfbloodbags , then you have script fn_selfActions.sqf in your MPMission,
3.1. Extract scripts lock_veh.sqf and unlock_veh.sqf from dayz_code.pbo to (in my case it D:\SteamGamesLibrary\SteamApps\common\arma 2 operation arrowhead\MPMissions\DayZ_Epoch_24.Napf\Scripts )
3.2. in your MPMissions fn_selfActions.sqf replace references to extracted scripts (lock_veh.sqf and unlock_veh.sqf).
Part of new fn_selfActions.sqf : http://pastebin.com/QgHM4k5e
4. Modify extracted scripts lock_veh.sqf and unlock_veh.sqf like this:
lock: http://pastebin.com/v7EiUerT
unlock: http://pastebin.com/n8JYivtq
5. start server.
Additional bonus - car lights will be flash when car lock\unlock
PS: sorry for my english.