No go, really. I use position packets sent by the client, and add a weapon to them. The delay between those packets is, by default, 100 milliseconds. This delay varies a bit as ships send far more packets when they thrust, rotate or fire weapons themselves (although position packets with weapons attached aren't used by extraweapon). This works fine for bombs and specials like repels/bursts (doesn't really matter if those fire right after one another or after a small delay), but for really rapid fire guns it doesn't work too well. A shredder-like delay is the best I can do.