You won't be able to use the editor, but you can utilize a script. Here's one that works for me.

Explanation of how it works:
Name the Tank: In the editor, name your tank under the "edit" and "variable name" fields.

Assign AI to the Turret: Place an AI inside the turret and give it a name under the "variable name" field as well.

Set the Target Location: You’ll need to provide the AI with a location to look at. To do this, place an object at a random position. Then, go into the object's properties and note down its X, Y, and Z coordinates.

Script Behavior: Once you've completed these steps, the script will rotate the turret to face the desired location, and then it will delete the AI.

In my script:

Ps1 represents the tank.
As1 represents the AI.

By some reason the script only works if there is the // for comments!

The Script is an .sqf

Script:
As1 moveInGunner Ps1;
Ps1 engineOn false;

As1 moveInGunner Ps1;//
Ps1 engineOn false; //

//
_targetPos = [5678.245, 1491.062, 4.433];
As1 doWatch _targetPos;

//
[this] spawn {
sleep 2; // Give AI time to aim
deleteVehicle As1; // Remove AI, locking turret
};


IF THIS SCRIPT DIDNT WORK HERE IS A MORE COMPLICATED ONE BUT IT WORKS 100% everytime!

Here's how the script works: You add an object and give it a random name (in my script, I named it Po1). The gunner will then locate the object and rotate the turret toward it. After 2 seconds, the AI gunner will be deleted, along with the object used as a pointer. This method works every time!

As1 moveInGunner Ps1;
Ps1 engineOn false;

As1 setSkill ["aimingSpeed", 1];
As1 setSkill ["aimingAccuracy", 1];

As1 doTarget Po1;
As1 doWatch Po1;

[this] spawn {
private _lastDir = (Ps1 weaponDirection currentWeapon Ps1); // Initial turret direction
private _timeStopped = 0;

while {true} do {
sleep 0.5; // Check every 0.5 seconds

private _currentDir = (Ps1 weaponDirection currentWeapon Ps1);


if !(_currentDir isEqualTo _lastDir) then {
_timeStopped = 0;
} else {
_timeStopped = _timeStopped + 0.5;
};

_lastDir = _currentDir;


if (_timeStopped >= 2) exitWith {
deleteVehicle As1;
deleteVehicle Po1;
};
};
};