A PC-based program that allows you to update firmware in some Digitrax products is called DigiIPL. IPL stands for Initial Program Load.
2.8.1 - "If a product is not "Found" by DigiIPL, the software will still always send out the dmf file, and a correct target device will properly update."
Note: If you are running Windows 2000 you will need to put the mfc90.dll in the same directory as the DigiIPL.exe program for it to work. You can download the DLL here.