Run the Injector.exe or inject the dll using another injector.
NOTE 0:
Code:
Make sure you have the latest version (1.169) of BattlEye installed (From here
Replace the BEClient.dll in "arma 2 operation arrowhead\Expansion\BattlEye" and "C:\Users\your_username\AppData\Local\ArmA 2 OA\BattlEye"
NOTE 1: A log file will be created in the same dir as the dll.
NOTE 2: This doesn't bypass server-side Script Detection (New Script Logging) be careful what you execute.