RESOLUTION
The complete procedure is described in Backing Up and Restoring Your System article in HSPcomplete Subscriber's Guide.
Also, client side backups are just gzipped tarbolls, so to restore it should be enough to upload backup file inside the VE (using FTP client or SSH client) and use tar to restore files from the backup with overwritting existing files, just for example:
# tar xzvf backup_server.000example.com-2007-05-12-00-24.hspc-bak -C / Keywords: VE client side backup