på YouTube visar [APS]Gnat en film där han med scripting lyckats med att skjuta från fordon med handeldvapen.

All done with just script bits from UNN and WarWolf/Mr Flea
UNN - 3D placement script
WarWolf/Mr Flea - Key capture script

Once you work out the relative 3D coordinates of where you want to be in the vehicle, you then "hold" them there with a fast loop that doesnt seem to affect fps. Its a very smooth ride.
Then using the normal A and D keys you can rotate left and right. Only really works well if your "Float Zone" slider is all the way to the right.
Later part of the video shows a chopper being attached to a moving ship. Same principle.
Works pretty well in SP, not sure what MP performance would be / could be, but I don't expect it will be so easy in MP.

I'll post some code once I tidy it up.