apt-get install qemu-kvm libvirt-bin dnsmasq-base
/etc/libvirt/qemu.conf (not necessary if tunneling ssh):
-- vnc_listen = "0.0.0.0"
don't forget to restart libvirt-bin

Set up bridge br0 on eth0:
/etc/network/interfaces:
Remove auto eth0
Add:
auto br0
iface br0 inet dhcp
bridge_ports eth0

To create a new guest see virt-install