Move external iTunes library files to different location without losing metadata
Solution 1:
The locations are hard-coded, absolute not relative, so you need to find & replacefile:///Volumes/Macintosh HD/Users/[yourname]/Music/iTunes/
with the actual path - file:///Volumes/mountpoint...
This would have been a single step find/replace on the iTunes Library.xml [which it is far better to keep in its original location even without the added complexity of a remote write] using something like TextWrangler/BBEdit if the library was consolidated to start with. As it isn't, you might have multiple steps to do, depending on how broad your "path-scape" is. .
It's been quite some time since I did this - the next step doesn't seem to work the same as it used to - see iTunes: Moving iTunes Files (Self Managed)
Breaking the .itl no longer works with recent iTunes versions - it just complains it's damaged & makes a new one itself, which loses everything.
I think last time I tried it I think I just left the .itl as it was & it ran OK (I'm open to correction on that if someone cares to try it, I'm not going to do it 'just to see' ;)
Related & possibly worth a read-through too, for general background & it also covers recent iTunes variations in method - How to share an iTunes library between Mac & Windows?
BTW, I think you ought to still be able to use 'Organise Media' using a remote library - though mine is just on a different drive, not a different server, so I haven't tested that scenario.