Never tried, but it should be doable.
First create a tar with the VM data:
vrituozzo# cd /vz/private
virtuozzo# tar cf myvm.tar --numeric-owner VMID
Then move it to the proxmox node and extract it:
pve# cd /var/lib/vz/private
pve# tar xvpf myvm.tar
Then you need to create a config file in /etc/vz/conf/.
I guess its best to first create a dummy vm on the web interface with the settings you need, and then simply copy/edit that file.
let me if itf that works.
- Dietmar