GoAnywhere allows you to upload/download files to/from your AS/400 (iSeries) without the use of the iAccess client.
GAMFT seamlessly connects to your AS/400 for Command execution, as well as, Database access. (Both through resource definitions)
If you're wanting to just upload a file, you can utilize plain FTP to place the file (IFS or Library). You can also utilize the FileShare (through OpsNav) connect and just place the file into the IFS as if it's a local folder.
There are several ways this can happen through GAMFT.
And yes, if you want to continue going through the iAccess and use the DTT file to upload, you can call a local BAT file and execute that as well. :)