The source should come out once the 3.0.2 becomes official, and not an early preview.
And, yes, several users already have replaced the kernel on K2 devices, check this forum
.
(if you don't want to touch the core kernel, and just want to inject modules, your x-compile toolchain will have to match *exactly* the one used by the lab126 guys (ie. K 2.6.26, glibc 2.5, binutils 2.18.4 (not sure about binutils right now, something like that xD), gcc 4.1.2).