I testet on a Centos 4.0 that is equivalent to Red Hat Enterprice server 4
It seems like there is sligetly small differences for the syntax/command set for ifconfig.
OK, try this:
ifconfig eth0:0 192.111.0.5 netmask 255.255.255.0 broadcast 192.111.0.255
And if this not work, only this:
ifconfig eth0:0 192.111.0.5
And then check status:
ifconfig.
By the way I made a copy past on your command string and tested it here. Worked like a dream here, so you have not done any mistyping either ..
Hope it work snow

Arne.