Create an empty LU slice :
lucreate -s - -n <BE_NAME> -m /:/dev/dsk/<DISKSLICENAME>:ufs
Then install your FLAR:
luupgrade -f -s /solaris/install/image -a /<FLAR> -n <BE_NAME>
If necessarey, lumount your new BE and fix things within /etc/hosts, /etc/hostname.* /etc/vfstab, etc......
Acitvate and reboot to the new BE.
More info in the Live Upgrade users guide.