apt-get install module-assistant kvm kvm-source
m-a prepare
m-a a-i kvm

modprobe kvm_amd (or the intel kvm module, in case you're on intel)

create images:
qemu-img create -f qcow someimage.img 10G

install:
sudo kvm -net nic -net tap -hda root.img -hdb swap.img -cdrom someimage.iso -boot d -m 384

run:
sudo kvm -net nic -net tap -hda root.img -hdb swap.img -m 384