http://blog.andreas-haerter.com/2011/06/18/ubuntu-festplattenvollverschluesselung-lvm-luks

Manual installation of LVM etc. and Ubuntu
                                    ======
http://wiki.ubuntuusers.de/system_verschl%C3%BCsseln

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Following Howto and script didn't work for me  :-(

( http://community.linuxmint.com/tutorial/view/344 )

Mint
====

Easy Full System Encryption with Linux Mint (Howto)The following HOWTO is an easy to use 
automated script to install a fully encrypted Linux Mint using LVM and cryptsetup. 
This works for new installations only and you will need internet access during the installation 
process to download a scipt.

The script is originally made for Ubuntu but works perfect for Linux Mint 10 (Ubuntu Version).

How to use it:

Boot from your Linux Mint Desktop from your Installation Live DVD/CD

Open a terminal (press ALT+F2 and type gnome-terminal or xterm)
type or copy & paste:

wget "http://readm3.org/_export/code/os/ubuntu/full-disk-encryption-lvm-luks.sh?codeblock=1" \
-O "/tmp/full-disk-encryption-lvm-luks.sh" && chmod a+rx "/tmp/full-disk-encryption-lvm-luks.sh" \
&& sudo "/tmp/full-disk-encryption-lvm-luks.sh"

Press enter, this downloads and starts the encryption script

Follow the instructions in the script and answer a few questions about patition sizes

Start the installation of Linux Mint from the DVD/CD when you're being asked

At the partitioning section of the installation, you will need to choose "manual partitioning" and 
change the mountpoints which are stated in the script. Take extra care when changing the mountpoints 
as any mistyping will result in a non functioning system.

You are being asked to change one mountpoint to the destination "/root". As Linux Mint has a 
slightly different setup, you will need to choose "/" instead (slash only)

After the installation is finished, do NOT reboot, but click "continue trying Linux Mint"

The script automaticaly finishes it's work (installing the bootloader)

DONE
 
Thanks to Andreas Haerter who wrote this script which can be found in source code here:
http://readm3.org/os/ubuntu/full-disk-encryption-lvm-luks.sh