Your question says "passengers". I chose my reply with this in mind. If you want this feature for DJ work, that's a different thing entirely.

The answer is no -- there is no way (currently) to accomplish this.

What level of ease-of-use do you want for this? It could be as easy to implement (but slightly harder to use) as a shell script that auto-numbers the stuff on the player.

Alternatively, someone could cook up something easy to use, that would require more effort to implement. It's not that difficult -- the synchronisation protocol is public, and there's plenty of information around.

But, no, this feature will not be implemented in this form in emplode. It's a PITA, frankly. Like I've said many times, the correct way for me to implement this kind of functionality is by scripting. This will hopefully happen after v2.0-final.