Aha, I see. In that case, this may or may not be a job for
FWatch, either that or some other form of key/mouse command interception (there is a script that doesn't require a new exe and an addon, but unfortunately it is limited in the keys it can pick up). Then you just create a missile based on the type of vehicle the player is in (and if you want to make the missile script very generic, without typeof checks, then make sure you create the missile well away from the vehicle position, perhaps adding some nice drop effects until you do create the missile)
EDIT:
Ok, so you want to do all of this when the player is driver, and create the missile in the direction he is looking in. This might be impossible, unfortunately. But, with getdir, plus the vehicle-angle detection functions (
GetBank etc) you would be able to fire the missile in the true direction that the
vehicle is pointing in. Compromise?
EDIT2:
This might be possible in Fwatch. Simply wait until the player mounts the vehicle, then run a mouse-position-fetching script with a short delay to query the mouse position from FWatch. This, combined with a small amount of trivial vector maths (I'm happy to do it) would get you your player's viewing direction. The key lies in the fact that the player's view direction snaps to the vehicle direction when the player mounts a vehicle. As I said before, this requires a new exe and one addon for all who want to play the mission. Compromise? ;D