The box on top of my Receiver in the pictures is the Ethernet converter, it needs power ( 5v ) and an ethernet patch cable to the Receiver. You put a PCMCIA 802.11b wireless card in it, and then your Receiver becomes Wireless. I also use one in the car with my Empeg. Works just fine.

Downside is ~£250 for the Ethernet Converter, plus ~£80 for 802.11b card.