As long as you have workable Linux system on the drive you can install bootloader and use it to boot the system. For example it can be GRUB. Lilo would work as well. After installation you will have to configure it and point out which kernel to boot and where it is. For that you need to know what partitions are on the hard drive and where is kernel.
First, see structure of the hard drive by doing fdisk -l
After that try to mount partitions with default settings. Hopefully Live CD system will be able to do that. If no, you will have to try to mount them manually.
Take a look at /etc/fstab on the Linux system on the hard drive. It may reveal filesystem and other useful data.
Could you post output of fdisk -l ?