This is only if you have RTH and if you go on Xlink or XBL Ok so what this does it if you are host and change the projectial EVERYONE will be able to see the proj. So first open your map in alteration. Push Ctrl "C" To Coppy This Number Now Go To The Worthog Troop Effect That You Used. Push Ctrl "V" To Paste That Number in This Box Then You Can Change What You Want To Shoot Out Right Here And There You Go. This Makes Xlink SO much more fun
The only part I would change is nulling the projectile. Just set it to the projectile you want, and still do the effect changing part. The reason for this is because changing certain things will give the kill to the guardians as opposed to the player. For example, I made it so that the shotgun shoots plasma grenades at the speed/distance/range of shotgun bullets but if you leave the shotguns projectile nulled everyone can see it but your kills don't count (that was a run on sentence). So instead of nulling it, just change it to the projectile you want to use and then continue with this guide like you normally would and then everyone can see it and the kills are counted correctly.
It works fine in windows 7 64 bit, that is what I am using. Some versions don't work with the aero theme in vista or 7. You can either get a version that doesn't have that problem or change your theme to a "basic" theme.