Each individual DVD disc I load in my changers is first added to my DVD Profile. DVD Profiler assigns said DVD a collection ID. I then load that DVD in my changer according to its collection ID.

Collection ID's 1-400 = Changer 01 (Slots 1-400)
Collection ID's 401-800 = Changer 02 (Slots 1-400)
Collection ID's 801-1200 = Changer 03 (Slots 1-400)
Collection ID's 1201-1600 = Changer 04 (Slots 1-400)

In my pcf file each of the DVD changer devices contain macros 1-400 which load each of the changer slots. Said macro not only loads a given changer slot, but also cueues up the rest of my home theatre system accordingly, then jumping to the transport controls for that changer. As such, when adding a DVD cover to my remote via PPENG I simply link that DVD cover image button to the corresponding marco.

-Lowpro