first see if its enabled by doing
if its not showing up then u will probably have to find the driver that your card uses and uncomment the line from /etc/rc.d/rc.modules
eg: my netgear FA311 uses natsemi driver, so in rc.modules it looks like
if it is showing up in ifconfig
you could try putting this in /etc/rc.d/rc.inet1.conf
# Config information for eth0:
doing that should set the ip when the box boots.
or set it using netconfig, then reboot or run /etc/rc.d/rc.inet1
u could also try
ifconfig eth0 10.0.0.1 netmask 255.255.255.0 broadcast 10.0.0.0
those are the only ways i can think of how to set the ip, lemme know if it helped.