Well in my script I tried (gunner _Tank1) dotarget _Target1, but it seems that doesn't work. Also with getting the tanks to target the barrels like that when the tank turns the barrel doesn't so if the turret did move it'd then be pointing in the wrong direction.
I think the tank won't target in 'safe' mode because the driver is 'turned out' so the turret can't turn (else it'd squish his head.
) I'm not sure if it's possible to turn the driver and commander in, in 'safe' mode. But if you can, then that might work.
It probably involves a lot of tinkering about with. :-\
Oh yeah, I forgot to mention..
I'm not sure how you'd designate a certain unit inside a vehicle but you could make a looping script using the "Unit1Name DoWatch Unit2Name" command...?
I did try using 'dowatch' zsa_zsa_rasputin, but the whole tank turned towards it's target not just the turret. So, nope it didn't work for me