Virtual Machine Pools- How to configure-use

What is the best practice used to assign ip numbers to a pool of virtual machines?

I prepared a template to be used as the base for a vm pool. I assigned 2 vm's to the pool. I had to configure by hand the first time they booted as to what keyboard, ip number, dns router info they needed.

How can these be 'throwaway images' if I have to do that?

Thanks in advance.