Try simply installing "pmount" from Package manager.
Brief description from synaptic:
mount removable devices as normal user
pmount is a wrapper around the standard mount program which permits normal
users to mount removable devices without a matching /etc/fstab entry. This
provides a robust basis for automounting frameworks like GNOME's Utopia
project and confines the amount of code that runs as root to a minimum.
This package also contains a wrapper "pmount-hal" which reads some
information like device labels and mount options from hal and passes
them to pmount. Install the package "hal" if you want to use this
If a LUKS capable cryptsetup package is installed, pmount is able to
transparently mount encrypted volumes.
Canonical does not provide updates for pmount. Some updates may be provided by the Ubuntu community.