I think that kernel build instructions should be added.
It's as simple as checkout from git, and make changes, then make, preferably with the NDK. (codesourcery toolchain pumps out code of dubious reliability, based on my tests with a Tab 8.9)

EDIT: Hmm, it seems that WiFi being connected makes the battery burn. However, I was using the phone <3 feet away from the router. Does the driver just set TX power to maximum?