Here is the MIDI map that I use for the Roland TD20 and TD20SX.
1. Reinitialize factory settings on the Roland Module.
2. Download this file
3. Unzip this file
4. Place the contents (2 files) into your Maps folder located with your documents.
5. Launch BFD2 and do a Trash and Rebuild
6. Set your Roland module to the first preset and start playing.
I have confirmed this works with the TD20SX. Roland told me that the note numbers will line up with the TD20. I have done a few clinics on brand new Roland TD20SX kits and never had a problem. Good Luck!