I would have never thought of doing this until I saw the question. I of course had to run home and start installing and reinstalling
I figured out that ffxi uses installshield with 3 separate installs
So I copied the playonline folder (only this folder is needed) off the first disk
Contents of disk 2, 3, and 4 (the install for FFXI) into another folder
And the contents of disk 5 (the expansion) into its own folder
Then I used the info from unattended.msfn.org's
InstallShield to create unattended installs and a .bat file to run each install.
So now game installs with a single click. Now if I can just figure out how to update unattended…