I am happily doing wireless, using Lucent / Orinoco / IBM kit. Orinoco access point is in the house, in the car is a box called an Ethernet converter, into this box you insert a wireless PCMCIA card ( I have tested IBM and Orinoco ones ), a patch cable joins the box to the Empeg sled. The box needs 5v power supply. You should find the kit pretty easy on the wavelan.com site. The clever bit is the Ethernet Converter.

I could do with another Ethernet Converter, but they are a little expensive, do post if you find them cheap anywhere.