We did this. We created templates for the HTTPServer, WAS/WC server, and DB2 server. For WAS/WC, product installed but no instance created. It has been a while so I don't remember exactly what all needed to be changed. For WAS/WC, you can use wsadmin to change the hostname. On our servers we had other things already installed so it wasn't just the Websphere stuff I needed to find where the old Template name was. You can write a little shell script using find and grep to search text files for the Template name (in our case) and change where necessary.
Have fun.