I would say, use dpkg-buildpackage and later read up on all this. It is a tiny bit complex, and extends to more *nix structure knowledge (not to mention the extra tasks involved in cross-compiling.

My building the kernel is a bit slowsome (VERY old computer, VERY limited HD capacity), so if you want to experiment a bit yourself, I attach my rm581_defconfig that you may copy to arch/arm/configs/ and do the dpkg-buildpackage. It SHOULD include what is needed for NAT.