Actually, I got it.
I changed the following files:
/etc/hosts
/etc/nodename
/etc/hostname.xxx (network interface)
/etc/net/ticlts/hosts
/etc/net/ticots/hosts
/etc/net/ticotsord/hosts
/etc/inet/ipnodes
I found these by running find . -type f -print | xargs grep -i HOSTNAME, where HOSTNAME is the name of the machine.
Thanks for reading.
I don't like sys-unconfig -- too much manual intervention is needed.
You could simply write a script that'll go and change the entries in the files listed (above) and also do a vxdctl hostid <newname>(to change the veritas hostname configuration as well -- check the vxdctl manpages for more detail).