Digitrax DCC systems can program  decoders using Blast Mode Programming on the Mainline.  Blast Mode Programming will program EVERYTHING sitting on the main line track so, you MUST remove everything from the track that you are not programming or use an isolated piece of track connected to Rail A & B.

NOTE: Track power must be ON during Blast Mode Programming.
You will not be able to read back CVs using Blast Mode Programming.
To use Blast Mode Programming with Zephyr, close Option Switch 7.
1. Press the "PROG" key.
2. Press the "SWCH" key.
3. Press "7".
4. Press the "c" key (located just below the "9" key).
5. Press the "EXIT" key.
6. Program the decoder using Direct (dir) mode.  Be sure that ONLY the loco with the decoder is on the track during programming!!

When you are finished programming, you must reset Option Switch 7 to "t" to disable Blast Mode Programming as follows:
1. Press the "PROG" key.
2. Press the "SWCH" key.
3. Press "7".
4. Press the "t" key.
5. Press the "EXIT" key
You have now exited Blast Mode Programming and can return to normal layout operations.

Hope this helps.