you can suspend to swap or even to a file, I never did the last one.
If you want to do suspend to swap, you need to append this to your lilo entry, can be done easily with vasm:
Where sssX is your swap device. If you dont know which is your swap you can run
fdisk -l | grep swap
Now you have to reboot or run at least once the following command:
echo swap:/dev/sssX > /sys/power/tuxonice/resume
Again sssX must be replaced with the proper value. If you didnt change the default configuration you can run hibernate without arguments to use suspend to swap.