This Tutorial explains how to add an invite all button to your browser. It is much more effective and easier than the invite all code.
I am releasing a promotional trade secret I discovered on my travels due to the apparent new ineffectiveness of invite all codes...This method uses advanced promoter ninja tactics to invite your friends to events! Its constantly upgraded as well by the author.
first you must have Firefox in order to do this.
from inside firefox install the greasemonkey found here
now install the invite all script for the app
1) go to facebook event page
2) click “+ select guests to invite”
3) on the top right of the invite all box there should be a new tool bar
just leave the default settings on and click select all (if you have allot of friends it may freeze your browser for up to 10 minutes. just leave it alone)
IF YOU ARE ON A MAC THIS IS THE ONLY WORKING WAY TO DO INVITE ALLS