tried all of that and unfortunately... yeah but nah.
GarageBand does like aliases because all my spectrasonics stuff has been setup like that and they work no problem it just looks as though GarageBand's sampler is coded to only talk to that location for some reason.
At the end, as they say, it ain't no biggie as I hardly use those instruments anyway I'm just one of those attention to details guys... occasionally :)
Speaking of which, Soundtrack Pro is another matter. I moved the Apple loops for that too and that's given me more grief than GarageBand and you can specify your paths in that package. Have you noticed there are two separate Soundtrack pro apple loops locations? One is much smaller and has the older power loops and artist loops in aiff format, whereas the newer folder has caf verions of the same files and more. Me being me, I thought, I know, let's streamline this a bit more and just have the one folder... but no. The loop browser shows double ups of the files yet one is red and the other is auditionable.
Sodding annoying that's what it is!