It is probably not an issue anymore, so it is just for posterity.

I found good answer at: http://www.linuxquestions.org/questi...noppix-471366/

Here is summary how to mount LVM disks:
knoppix# vgscan --mknodes
Reading all physical volumes. This may take a while...
Found volume group "system" using metadata type lvm2
# vgchange -ay
3 logical volume(s) in volume group "system" now active
# lvscan
ACTIVE '/dev/system/home' [20.00 GB] inherit
ACTIVE '/dev/system/root' [15.00 GB] inherit
ACTIVE '/dev/system/swap' [2.00 GB] inherit
# mkdir -p /mnt/root /mnt/home
# mount /dev/system/root /mnt/root
# mount /dev/system/home /mnt/home

More about LVM is on:
http://www.ibiblio.org/pub/Linux/doc...LVM-HOWTO.html

Hope it helps to the next person.