You can also achieve this with this procedure:
1) Create your target virtual machine
2) Install a minimum version of the same operating system that your source has (network, ssh server and tar must be available)
3) Create a list of directorys we don't want to include (boot, proc, dev, sys, etc/fstab, etc/lvm, etc/blkid, mnt/yourexternalhdd) and save it under /tmp/nocopy
4) Take a snapshot of your target in case something goes wrong
5) SSH to your source and as root:
cd /; tar -zcvpf - -X /tmp/nocopy * |ssh target "cd /; tar -zxvpf - --numeric-owner"
6) Reset target.