Well, not knowing much about Morphix....I've only done this with a rescue disk, which automates the process somewhat.
Assuming that Mandrake is gone, try using the live cd boot. How you edit lilo (if the live cd allows the edit, as some distros have lilo protected as root) depends if lilo is protected as root or user permissions.
Yes, /etc/lilo is the file. Look at that file and make sure that it is indeed there. If so, make sure that at the beginning of lilo, the lines something like
lba32
boot=/dev/hda (assuming that hda is the mbr location)
The key is the boot=/dev/hda, which signifies installing lilo on the mbr. If it is not installed on the mbr, it will say something different, say if lilo was installed on a boot partition other than the mbr. Edit this if necessary and save the changes. If Morphix Live cd does not auto mount the partition that it is installed on, then at a console, issue the following commands;
mount -t ext3 /dev/hdxx /mnt (xx= the partition where Morphix is installed on. If you have not been able to modify lilo, try it after issuing the next command)
chroot /mnt
/sbin/lilo
Just make sure that you look at and modify, if needed, the lilo file to see if the boot= line is correct, before running the /sbin/lilo command.
Lilo, unlike Grub, needs this last command to actually write the information on the mbr.