Well, yes, sort of. SecureFileTransferClient is a Java class, which won't work, but you can use SecureFTPConnection, which is the main class for our .NET FTP component, edtFTPnet/PRO. Below I've included a JSS sample, which I just tested as the JSS script for a process trigger. Please also refer to the edtFTPnet/PRO User Guide and Examples. I'm not aware of anyone else doing this before, but, as far as I can see, it should work fine.
try {
var ftp = new EnterpriseDT.Net.Ftp.SecureFTPConnection();
ftp.ServerAddress = "myhostname";
ftp.UserName = "myusername";
ftp.Password = "mypassword";
ftp.Connect();
ftp.Close();
console.log("FTP OK");
} catch (e) {
console.error(e.toString());
}
Please be aware that, although you're accessing a .NET class, the code is actually Javascript as evidenced by the syntax in the catch statement.
SecureFTPConnection has three methods similar to executeCommand, namely InvokeCommandSSH, InvokeFTPCommand and InvokeSiteCommand. I'm not sure, which one you need, but I think one of them should do what you need.