I finally got the Zonet ZEW2501 USB Wifi dongle working with the 2.6.22 kernel in Ubuntu. It was quite a hassle. If you can, shop around for something which linux plugs ‘n’ plays with, rather than going through all this. But I would guess that if you found this post, it’s probably too late.
So on to the guide (I posted it on the ubuntu forums): http://ubuntuforums.org/showthread.php?p=3191237#post3191237