If byte 0x6a in the CMOS has its top bit set, the wireless check will be disabled. There is a DOS program to do that here. I have no idea who wrote this program. This must be run under real DOS, not the Windows command prompt.
There is Linux code to do this here - this code was written by Vojtech Pavlik and modified slightly by me to do more error checking. It needs to be compiled and run as a user who can access the /dev/nvram device.
If you make use of these hacks, please get in touch with IBM and tell them that you're unhappy with their policy of restricting the cards that you can use. Go to this page and then click on your country. Call the customer services number given and make a complaint. Enough complaints will encourage IBM to either change their policy or make it clearer what they're doing and why.