Notes taken from the dislocker man page.
Make mount points
mkdir /mnt/ntfs
mkdir /mnt/clear
Mount the drive, and prompt for the password
dislocker -V /dev/sdc2 -u -- /mnt/ntfs
Then mount the drive as read-writable
mount -o loop /mnt/ntfs/dislocker-file /mnt/clear
Then once you're all done, unmount
umount /mnt/ntfs
umount /mnt/clear