This is quite long to reproduce, so please don't miss any step.
You need 2 mods;
1- FFIS (http://www.armaholic.com/page.php?id=22096)
2- Proving Ground (http://www.armaholic.com/page.php?id=21226), you can replace PG by any other script using a bullet-cam but this tool is essential for this kind of thing I want to say.
3- Once mods installed, go to editor, add a soldier, preview.
4- Pause the game and turn on Proving Ground, and open the PG's menu (scroll down at the action menu)
5- Enable bullet-cam and click on Environment, this is including weather, viewdistance, wind force/direction, etc. Max-out winds force.
6- And finally, fire in the wind direction.