Palantir gets the database via a plugin to jEmplode, the 3rd party java program that is used to sync songs to the empeg. The plugin turned the database into a Palm specific file that was then synced via the Palm software. IRDA was used to send playlists and other commands from the Palm to software listening on the empeg, that in turn controlled the player software.

Since modern devices lack IRDA, your approach of using the network with a router in the car is the right way to go now. Or, alternatively, a Bluetooth to Serial adaptor on the back of the empeg, though this limits bandwidth to 115kbit, vs the possible 10mbit via the router.