Ftp With Custom Commands?

I wrote a program that read a text file, find some specific text and eventually replace it with other. This works fine but after the file creation I have to ftp MANUALLY to my AS400, putting the file and finally run a specific command.

Here's the question, I saw that I can use FtpWebRequest but it only permits to download, upload and so on, I need to run a custom command (passing a string).in other words here's what I need:

user = "me"
pass = "you"
host = "as400"

ftp.Credentials = New System.Net.NetworkCredential(user.Text, pass.Text)'now the connection is opened put my file send custom command