to my knowledge, BMW changer must say BMW, even though it might be manufactured by Alpine - there is a BMW proprietary hardware installed on otherwise regular changer to communicate with BMW's iBus. BMW never licensed iBus outside of its vehicles, even though the bus has been hacked and reverse engineered...

it seems that your changer needs the following to operate in E53:

Alpine CHA-S634 6 Disk CD/MP3 Changer
Alpine M-Bus to AiNet Adaptor (KCA-130B)
Soundgate BMW to Alpine Changer Interface (ABMW35V5)