I would use a knoppix live.
To access the lvm you have to digit into the terminal
#lvm vgchange -ay
this will display your volume group and logical volume names
than you can make a dir with mkdir to mount your LogVol and copy your data
#mount /mnt/rescue /dev/VolGroup00/LogVol00
using the correct volgroup and logvol number
I just recovered my data this way. Hope this helps