Check this link out:
http://astro.temple.edu/~moshe/intersil/
I've used this method, using a Syntax USB-400 USB dongle I bought on ecost a year ago for about $12. I used the D-Link 1.4.7 driver mentioned on the page linked to above, on Panther (can't remember which version at the time), on a G4 ibook, and it worked fine.
The Syntax USB-400 dongles sell on ebay occasionally, usually for under $10 - none available right now, though.
I also did a quick search for other current sources of this dongle, and couldn't find one - it's been out of production for quite a while.
To add to that, one of the advantages of a USB dongle if you're having reception problems: - connect it to an extension cable and move the dongle to someplace with better reception. With one or more
active USB extension cable(s), this distance can be up to 64 feet (hang it out the window, even, if it's not raining).