ooops, quick syntax fix here. I forgot to add the portfw part of the commands. Here's a revised example.
example 1 (with no ftp daemon running on gateway box)
ipmasqadm portfw -a -P tcp -L 209.19.19.2 21 -R 192.168.1.2 21
example 2 (ftp daemon also running on gateway box, so we redirect port 4040 to the ftp services on the winbox
ipmasqadm portfw -a -P tcp -L 209.19.19.2 4040 -R 192.168.1.2 21
regards,
JE