Howtoforge posted a guide about installing KVM Guests with virt-install on Ubuntu 11.10 Server

Unlike virt-manager, virt-install is a command line tools that allows you to create KVM guests on a headless server. You may ask yourself: "But I can use vmbuilder to do this, why do I need virt-install?" The difference between virt-install and vmbuilder is that vmbuilder is for creating Ubuntu-based guests, whereas virt-install lets you install all kinds of operating systems (e.g. Linux, Windows, Solaris, FreeBSD, OpenBSD) and distributions in a guest, just like virt-manager. This article shows how you can use it on an Ubuntu 11.10 KVM server.

  Installing KVM Guests With virt-install On Ubuntu 11.10 Server