Gentoo Keepalived HOWTO Brian Jackson 1.0 2004-12-28 Working with Keepalived
Installing 
# emerge keepalived
Configuring Keepalived

I suggest you start with one of the config examples from the doc directory for keepalived.

Also, see http://www.keepalived.org for documentation. 

# gzcat /usr/share/doc/keepalived-1.0.3/keepalived.conf.sample.gz > \
  /etc/keepalived/keepalived.conf
Starting Keepalived 
# rc-update add keepalived start
# /etc/init.d/keepalived start