You could check out my post on the Rio Receiver BBS. The equipment is the same whether you are using an Empeg or Rio Receiver wirelessly. The Orinoco Ethernet Converter costs about $190 and the wireless card (Orinoco Gold or Silver) is around $90. With this setup, you should be able to connect to any wireless access point.

There are other access points that will allow you to use it as a client such as the Linksys WAP11. However, this only officially works when you're hooking up to another WAP11-based network. IMHO getting that kind of setup to work is not worth the time or money.

EDIT: I forgot to mention that I got the Orinoco stuff from Provantage.