Using LVM for "/" partition
Unlike when using normal partitions, you can't use root=/dev/mapper/lvm-location in lilo.conf to specify the root partition. The reason is that lilo converts that location to /dev/dm-0, or /dev/dm-1, or whatever it happens to be mapped to at the time. The problem with that is /dev/dm-* are dynamically allocated at boot, and are likely to be different every time.
To get around this, the root location needs to be added to the 'append' section, so it is added to the kernel arguments untouched. It is also a good idea to add a rootdelay to ensure that the LVM volumes are ready before the system tries to mount them.