After installing the lilo rpm, you have to create a configuration file for lilo called /etc/lilo.conf and after doing that you need to write the configuration to the mbr by running lilo as root:
# /sbin/lilo -v
Here's an article that describes lilo configuration in more detail:
http://www.control-escape.com/linux/lilo-cfg.html
Be very careful when running lilo as an error in configuration could leave your system unbootable.