Found a script on the internet that does just that: itunes2m3u.py
Download the script, and make sure you find the iTunes Music Library.xml file. Copy both into the same directory, make sure you have python installed on your Linux machine, and execute the scripte with the iTunes Music Library.xml as argument:

~$ ./itunes2m3u.py iTunes\ Music\ Library.xml

It will dump all existing playlists in the iTunes library file as m3u files.

Import these into Amarok, and you're done.

Source for this script can be found here.