From Amarok Wiki

NJB media devices

This is VERY new. It can be found in 1.4.1+ or in SVN. Currently, you can view tracks on the device, upload and download, and delete. Playlists, tag editting and possibly streaming and other features are being worked on. You need libnjb and [libusb.sourceforge.net libusb].

Udev rules that give users in 'audio' group read/write access to the supported devices:

Add the following lines to a file under your udev rules directory, preferrable is to create new file for it (eg /etc/udev/rules.d/libnjb.rules).

SUBSYSTEM!="usb_device", ACTION!="add", GOTO="libnjb_rules_end"

# Creative Nomad Jukebox
SYSFS{idVendor}=="0471", SYSFS{idProduct}=="0222", MODE="660", GROUP="audio"
# Creative Nomad Jukebox 2
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4100", MODE="660", GROUP="audio"
# Creative Nomad Jukebox 3
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4101", MODE="660", GROUP="audio"
# Creative Nomad Jukebox Zen
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4108", MODE="660", GROUP="audio"
# Creative Nomad Jukebox Zen USB 2.0
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="410b", MODE="660", GROUP="audio"
# Creative Nomad Jukebox Zen NX
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4109", MODE="660", GROUP="audio"
# Creative Nomad Jukebox Zen Xtra
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4110", MODE="660", GROUP="audio"
# Dell Digital Jukebox
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4111", MODE="660", GROUP="audio"
# Creative Nomad Jukebox Zen Touch
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="411b", MODE="660", GROUP="audio"
# Creative Zen (Zen Micro variant)
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="411d", MODE="660", GROUP="audio"
# Creative Nomad Jukebox Zen Micro
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="411e", MODE="660", GROUP="audio"
# Second Generation Dell Digital Jukebox
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4126", MODE="660", GROUP="audio"
# Dell Pocket DJ
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4127", MODE="660", GROUP="audio"
# Creative Zen Sleek
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="4136", MODE="660", GROUP="audio"
# Third Generation Dell Digital Jukebox
SYSFS{idVendor}=="041e", SYSFS{idProduct}=="412f", MODE="660", GROUP="audio"

LABEL="libnjb_rules_end"

This should also work with MTP devices since it just gives normal permissions.