First off it does work. I tested by calling from my iPhone that is 1070 (Bria's softphone app rocks by the way) and I called a 5360 which displayed my desk phone ext (1005) and my tel dir name (M. Maynard) at the top. On the button appearance of the number I called it does show the name and number associated with my softphone (not sure if it is possible to change this). I assume that you wouldn't see the other number on a non-paperless label phone.
Programming:
Must have a multiline-set or hotdeck user programmed (1005 in my case, 2221 in question). Then create the PRG with 2221 as the PRG number. Then add the memebers that you want to ring and show (2222). You have a few other options that you can change if you so disire.
You also gain the "Handoff" capabilities that are available in a PRG, which I have not tested.
Hope this helps.