Give a look into /Library/Application Support/Logic, personally I moved the whole EXS Factory Samples folder, which in my case is around 10GB, but probably not everything there is strictly "essential".
I wanted to do something similar and for me the easiest and most flexible way is just using symlynks…
1) Close logic;
2) Locate what you want to move in the finder and move it to the new location. For example I just moved the EXS Factory Samples 10GB folder in /Library/Application Support/Logic/ to another HD;
3) In the terminal write
ln -s /drop\ here/the\ moved/folder "/path to the original location".
As always in the terminal you either put the path into "quotes" of use backslash\ before\ each\ space.
In my case this was:
ln -s /Volumes/JackBook\ Pro/Supporto/Logic/EXS\ Factory\ Samples /Library/Application\ Support/Logic/EXS Factory\ Samples
4) Open Logic and it will work without knowing the difference from before.
With this method you can chose what to move where and actually have a library spanning multiple HDs if you want.
I have a plugin that receives on midi channel 1 and 2 and I'd like to split my keyboard in Mainstage to get both channels to it.
Basically, I'd like to have the right part of the keyboard transmit channel 1 to the plugin and the left channel 2. Of course my keyboard only transmits on channel 1, so I have to find a way to use logic to retransmit on channel 2 what it gets on channel 1. I'm quite sure it should be doable in logic but still haven't figured how to do it.
Any idea?