+Finn Bartel, yes it is very Possible. This is how I do it on A PC in two steps.
Saving the Library:
- Create your custom brush and, from the bottom left corner of the library panel is a library icon, click on it to open a contextual menu that displays a list of brushes. But you realize the first option is Save Brush.
- On clicking SaveAs prompts you to save to the temporary/roaming location where illustrator keeps it data
C:\Users\YourLoginAccountName\AppData\Roaming\Adobe\Adobe Illustrator
17 Settings\en_US\x64\Brushes
- I advise you to save it in some project workspace folder say Project X Brushes.
- Copy that file using your explorer, navigate to the brushes preset folder and paste it there, mine is at..
C:\Program Files\Adobe\Adobe Illustrator CC (64
Bit)\Presets\en_US\Brushes
Where C is the installation drive. Note that you sometimes need administrator privileges to save under C:\Program Files.
That way your custom brush will show up in the Library. Also Note (You can group many libraries in a folder too within the Brushes folder)
Transferring the Library to the remote device:
- Just copy this file to the equivalent location on that remote computer
C:\Program Files\Adobe\Adobe Illustrator CC (64
Bit)\Presets\en_US\Brushes