According to the release notes for 4.4 its possible to use color palettes from GIMP: LibreOffice 4.4: Release Notes - The Document Foundation Wiki
I have found out that from the new color selector I can use gpl-palettes (from GIMP) if I copy the gpl-file from the GIMP palette directory (/usr/share/gimp/2.0/palettes/…) to the LibreOffice user catalog (/home/leif/.config/libreoffice/4/user/config/…).
But is there some kind of import function to avoid hard-copying the files manualy?
Cheers,
Improved my answer.
Looks like you can’t. You could try symlinking the GIMP palette folder as subfolder to the LO palettes folder. If that doesn’t work, you can symlink all of the palettes instead.
Symlinking will save you the trouble of updating the symlinked palettes in case they get updated. Even better if LO accepts GIMP’s palette folder as subfolder, which allows you to add and remove palettes at will without doing anything about the symlinks. I don’t have a Linux to test it right now, so I can’t be more sure.
EDIT: You could replace LO’s palette folder with GIMP’s while preserving the original LO palettes in the folder into GIMP’s. That’ll achieve same as symlinking as subfolder but will try to load same files in both programs, but how LO and GIMP will react can be known by 1 way only. Be sure to check the folder’s permissions and ownership before doing anything in case either LO or GIMP won’t like this new setup.
Symlinking the whole folder as sub folder to config folder doesn’t work unfortunately.
Adding another folder to the current configuration doesn’t work either. LibreOffice only accepts one Palette folder.
Adding symlinks individually to each .gpl file in config folder works great. I guess thats the solution for me 
Delete this answer.