Well first you need to grab autoit its self [
link]
Then mostly its just looking at other peoples scripts, and reading the help file.
Now the script above simply executes an *.exe installer, hopefully that of zonealarm. Next it simply waits for a given process to start...keep in mind that was a wild guess of mine of what Mailfrontier executable is named...so that may need to be altered...any ways once that process starts the script then continues...which is to kill that task and only that task.
So idealy the rest of your zonealarm installation should go fine.
So after you got AutoIt installed and the script edited to reflect the correct executables, you should be able to compile it into a exe its self...make sure the script is named different than the installer...other wise when the script is compiled it will replace the installer exe with its self...and to make matters worse...it would then repeatively reexecute its self...very very bad thing.