ITunes Resets to local Drive Space when External Hard Drive not mounted

Question

I have a large shared network drive where my son, my wintel box and I all have media placed on. All our computers are networked and authorized for each others music.
The problem is iTunes will default the 'iTunes Music folder location' to a local drive space if the external drive / path is not immediate available when iTunes is started (user:Music:iTunes Music vrs Eternal HD:Music:iTunes Music). This will sometimes will happen on boot, I have login mounting the external drive but that authorization / process once in a while times takes longer than starting up iTunes mostly due to an iPod connected to that computer. Since iTunes is not seeing that external drive (it isn't available yet). So the effect is iTunes defaults 'iTunes Music folder location' to the local music location - but - maintains the full library list (ie 10,000 question marks).
I have each computer maintaining it's own libraries on their respective drives which index to the music folders / files on the external (this is an itunes default to maintain the local library one each computer).
So ... How can I force iTunes to maintain the 'iTunes Music folder location' ?
(can the default location be changed ?... plist or some other file, or is this hard coded - or write a script to hold up iTunes to launch until after the external Hd is mounted)

Answer 1

I am sure that some will cringe at this
Note (my opinion) : I found when sharing with a Wintel box and Apple boxes it is better to use just smb. Mixing the smb AND afp arises to hang up problems and the afp is the side that seems to hang up the most. (that hurt me to type, I blame Finder - another story)
So - the script I use is fairly straight forward - Open Script Editor:
tell application "Finder"
mount volume "smb://[ip address of hard drive]/[drive directory you wish to mount]" as user name "[username]" with password "[password of said user]"
end tell
I recommend compiling the script (don't forget to save a copy you can also edit too - save as script). To compile a script : Save as Application, Run Only, No Start Up Screen. Since this has hard code Username / Passwords in the code - make sure you are happy with who will be running this script. So with the goal is to auto run when you start up, I tend to feel let it go ahead. If you wish to use afp (ie you are only sharing between macs - change the smb to afp in that code).
Next is to add this to your start up. Sys Pref > Accounts > Login Items
Just add the compiled application script to your user(s) login item.
Now for the - well, ugly part. Remove the iTunesHelper from the list.
Using Finder, Find iTunes - Show Package Contents, find iTunesHelper (it is iTunes:Contents:Resources)
Drag iTunesHelper into the Login Items (it should be listed now at the end of the list). Why this help I really can not tell you - I only have an idea of why - I have noticed that when my iPod may be plugged in when I reboot that iTunesHelper starts later in the sequence.
I did play around with changing the start up info on the unix side, for the brave only I would suggest. But - you can hard code a little better auto mounting a volume / hard disk / folder there on boot up. I did with to stay in the Mac GUI and AppleScript was just plain simple. The script can be modified to test if the volume is mounted etc time out try again etc etc etc... I kept it simple and straight forward.