the wifi driver in PR 1.3 is closed source afaik... By the way, why you need to modify sources? Are you sure you know what you are doing? Normally you would need kernel sources only for development... If you set up development environment on your PC, you can "apt-get source kernel" (I'm not sure how Nokia-made kernel package was named... if you are using kernel-power, then "apt-get source kernel-power" would be appropriate - and it has the open source replacement drivers for wifi). You shouldn't need to modify sources in normal end-user scenarios...