CheckHostIP not stopping known_hosts

Are there other settings on the server or other options to use
with -o to turn off known_hosts checking? I have multiple
hosts behind a firewall on different ports but try as I might
to use various options such as CheckHostIP=no and
StrictHostKeyChecking=no in various locations and on
the cmd line it just never works. Read the man page some
more, do a search, try different versions, yadda yadda.
Waved the red crystal but need the secret incantation...

OpenSSH_3.6.1p2 & OpenSSH_3.9p1, RHEL 3 & 4.