How do I make a new server a vserver host?

aptitude install util-vserver linux-image-vserver-amd64

Or

aptitude install util-vserver linux-image-vserver-686

Note - with a 686 machine with more than 4 GB of RAM, use linux-image-vserver-686-bigmem

Also - be sure to edit /etc/ssh/sshd_config and change the Listen directive so that the host only listens on the host IP address, not on 0.0.0.0 (which is the default and means listen on all IP addresses).