To build a customized kernel for natty you can follow the outdated wiki article at
https://help.ubuntu.com/community/Kernel/Compile
Use the information for Ubuntu Karmic Koala (9.10) and newer releases!
Follow these additional instructions to get it to work...


After unpacking the kernel sources and changing to the dir you need to set some execute-bits on scripts:

chmod -R u+x debian/scripts/*

Now you can modify the kernel config with this command:

DROOT=debian debian/scripts/misc/kernelconfig editconfigs

Say y/n for the config flavors and architectures you want to edit.
The DROOT setting is used in the scripts for paths to other scripts.
Without it there will be errors.

Afterwards cleanup with

fakeroot debian/rules clean

And start the build with e.g.

AUTOBUILD=1 NOEXTRAS=1 fakeroot debian/rules binary-generic