I was thinking you could probably write a script that would insert an "at" job into the machine to run an appropriate ifconfig command that would make the changes. Use a file with 3 columns to run the script with hostname, interface, new_ip as your seed data for the ifconfig command, also a new /etc/hosts file (Not sure how your environment is, but all our machines have the same one).
logically it would be something like
For every row in data file
telnet $HOSTNAME as root (or alternative if you like)
run at command with ifconfig $INTERFACE $IP_ADDRESS
logout
use secure copy to send new /etc/hosts or scriptable vi to make the necessary changes.
loop
There's still some work involved getting the files together but it's less than going to each machine and changing the information manually.
Or, get an intern =)
HTH,
Brian