You didn't say, if you use a PCMCIA adapter. If yes, it should be based on the quite new Atmel chipset (with a RFMD radio unit). There are drivers for Linux (http://atmelwlandriver.sourceforge.net), but you have to remaster Knoppix in order to get them work. I've also got an atmel-based wireless adapter and I have problems compiling the driver, so maybe there might be a solution here soon http://www.knoppix.net/forum/viewtopic.php?t=969

Hope it helps, seyring