I assume you've seen this?

Putting a DAB module through the FM interface would be pointless, there are far too many variables to control, kinda like controlling an MP3 player through a CD changer interface

Audio is MPX which the empeg decodes into audio and RDS. So your module will have to modulate baseband audio and generate an RDS carrier. Far too much effort. My solution is dead simple, just hang on and wait until I have some time to develop it.