DebianHelp has had a look at what it takes to get a wireless network up and running.
Enjoy the guide here:
I wanted to avoid running Sid/Unstable, so this meant compiling my own kernel with the RT2500 driver. In the entire process, this was the “difficult” part. Not really difficult per se, but certainly not plug and play. (It would be great if this driver makes it into Sarge/Stable and the default kernel.)
Debian's kernel team has worked up a great package called “kernel-package” which will easily allow you to build your own kernel *.debs and associated module *.debs. The first step is to configure your kernel. I stayed with the 2.4.27 kernel just to avoid fiddling with the newer 2.6 kernels and since the machines this will be run on won't need 2.6's new features.