First of all install dislocker, for doing that install aptitude and then
$sudo aptitude search dislocker
once you find dislocker install it, with:
$sudo apt-get install dislocker
once you have it installed, then you should run something similar to this:
$sudo fdisk -l
to discover your disk, and then
$sudo dislocker -u[YOUR_PASSWORD_GOES_HERE] /dev/sdb1 /mnt/hdext $sudo mount /mnt/hdext/dislocker-file /mnt/hd
