I have the same card running on Ubuntu. You need the restricted driver bcm43xx. If you can connect with a wired connection, do so, then install that restricted driver with Synaptic. You'll probably have to configure synaptic to use the "Universe" repository. It's in the options for synaptic (I don't have it in front of me, so I can't tell you exactly how to do it).
Synaptic is Ubuntu's package manager, in case you didn't already know. You get to it by going to the "Administration" option under the "Desktop" pulldown. At least, that's how it's done with Gnome. Not sure abouy Flux. You can always use the command line "aptitude" for an interactive, text-based front-end to apt, or simply use apt or dpkg. Man files will help you through this.
edited to add:
You may be wondering, "How would I know to look for bcm43xx?" Well, the answer is "lspci". If you run lspci in a terminal, it will spit back of bunch of info as to what's on your pci bus. Included in that list are the things plugged into your PCMCIA slot. You'll see the linsys card & it will mention something about using the Broadcom chipset BCM4306. That's the important bit.
Side note: oddly, Ubuntu did all this for me magically. I wonder why it didn't work for you? hmm.