maybe something like:

// stinger = shootMissile( "stinger" , getent( "stinger_start" , "targetname" ) , level.blackhawk , undefined , getent( "stinger_trigger" , "targetname" ) );

shootMissile( weapon , startPos , targetEnt , owner , trigger , offset )
{
	if( isDefined( trigger ) )
		trigger waittill( "trigger" );

	if( !isDefined( offset ) )
		offset = ( 0 , 0 , 0 );

	if( isDefined( owner ) )
		missile = magicBullet( weapon , startPos , targetEnt.origin , owner );
	else
		missile = magicBullet( weapon , startPos , targetEnt.origin );

	missile Missile_SetTarget( targetEnt , offset );

	return missile;
}

i dont know if this will work, im not into cod4 & sp stuff

but if this works, then:

- place a script_origin on the startpoint ( key: targetname value: stinger_start )
- define your blackhawk ( i dont know how this is done , i call it "level.blackhawk" in here ) in your script
- if you want to start the stinger-missile with a trigger, place a trigger ( key: targetname value: stinger_trigger ) in the map ( the script will wait untill the trigger is triggered if you define one )
- else you call the shootMissile()-function to shoot the stinger immediately
-if you define an offset, the missile will fly to this offsetpoint next to your target

stinger = shootMissile( "stinger" , getent( "stinger_start" , "targetname" ) , level.blackhawk , undefined , getent( "stinger_trigger" , "targetname" ) );

and place somewhere else in your gsc the shootMissile()-function



try it out on a small testmap to see if it works

take a look this map.
the scripts are from the "Hunted".