In your /etc/inetd.conf file, you will have to edit this to place the virtuald wrapper to accept connections for the FTP service. I changed mine to the following, where /virtual/conf.ftp is the configuration file for servers allowed to FTP in:
ftp stream tcp nowait root /path/to/virtuald virtuald /virtual/conf.ftp /path/to/wu.ftpd -l -a
If you are using tcp_virtuald, you will have to specify the above line as such:
ftp stream tcp nowait root /path/to/tcp_virtuald virtuald /virtual/conf.ftp tcpd /path/to/wu.ftpd -l -a