virt-install --paravirt --name webserver01 \
 --ram 512 --file /xen/ahoj.img \
 --file-size 1 --nographics \
 --location http://ftp.cz.debian.org/debian/dists/testing/main/installer-amd64/

Press Ctrl+] and you're back to the shell. Connect again to the running installation:

virsh 

virsh # console webserver01

A pro KVM s plnou virtualizaci:

virt-install -n densuke2 -r 512 --os-type=linux  --os-variant=debiansqueeze --arch=i386 --disk /srv/vm-test/densuke2.img,device=disk,bus=virtio,size=8,sparse=true,format=raw --location http://mirrors.usc.edu/pub/linux/distributions/debian/dists/squeeze/main/installer-i386/ --extra-args='console=tty0 console=ttyS0,115200n8' --nographics