Transfer Library/Application Support to another drive?

Question

Background:
I've got time ago a SSD drive, which is 90 GB, for my Mac Pro. I've decided to use it as startup
I've installed just the OS (Lion), and then I've used a regular HDD (500 Gb) as "home", so my desktop, music, documents and such does not go to clutter the small SSD drive.
Now thou, after about a year, I've almost filled that SSD, and I was wondering how is it possible.
First problem!  The Application folder
STuff downloaded from the store goes in that folder by default, and there is no option in the store to say "save the download here, and when I checl for update check there".
Told myself: this is easy, is  OSX! So I just made an Application folder on the drive where I have my home directoy, and copied most of the software that I don't use often, or that would not benefit from being on a SSD drive.
Now some works, but some other introduced the
Second problem! Library/Application support has a bunch of data that you cannot move.
Software like Garageband, Adobe, Logic and many others, save data there (which in some cases means GB and GB of data), which you cannot move, or the program won't run, or give errors because files are missing.
So, is there any way to tell OSX that I want this data somewhere else? The single app has no control over it, and I am not sure if this is even possible.
I want to move only some of these huge folders out of /Library/Application Support, so if I can selectively move folders would be great; otherwise I am just fine in moving the whole thing out to the regular drive...altho in part you loose the advantage of the SSD speed in this way, since every software will have to go to the other slower drive, to load config and main data.
Any suggestion is more than welcome!

Answer 1

Thanks for your reply.
Indeed that's exactly what I said. I am aware that the programs does not work, if I move the content, since I have already experimented various solutions.
And as final attempt I asked here to see if there is some way to achieve what I want: move selectively data out of the application support, on another drive.
I could buy a bigger one, but that would just postpone the same issue; to me the more logic solution is to ask the user where do they want to save their data, but so far I think that only FC asks it (I may be wrong; I installed these software quite some time ago).
As now I run without problem the system, even if my home is on a slower disk; my main objective is to have a quick boot and to speed up some software that I use the most, and so far everything works fine. The problem is just the space
After all OSX is Unix, there must be a way to create some sort of symlink that would make the OS happy, that's the only road that I ddn't pursue yet, but I would gladly avoid to do such a hack, to not cause disruption to the OS (it is a joy to use it, never crash or fail, so why pull the carpet under it's feet ? )