It's not impossible at all, just really hard to pull off (which is why it took a wizard to do it in FWTOW) - and I'm not sure it even made it in the release in the end (been a while since I've played)...
FWTOW uses somehow & somewhat remade & unoptimized engine, as I understand, that turned this DX8 game into DX9 with additional features to add more features. If you want to play.
I'm pretty sure the DX8 to DX9 port has nothing to do with the turret logic though. DX is just used for the rendering pipeline. But they did do pretty extensive hacking of the engine to get these things to work...