Sorry, you cannot patch finished kernel (almost). It is a monolthic executable, and only madmen like Borislav take open heart surgery approach on it (when no other options are left) . [1]

Mere hackers use source, modify it, recompile, try, modify.... When finished, they prepare modifications in the form of a patch, so that they don't have to distribute the whole source. Other, lesser hackers merely apply that patch to stock source, compile, install and use. Brave users simply use kernels others have compiled. Ordinary users use empeg kernels.

[1] Relatively novel approach is to have as much of the kernel as practical compiled in the form of loadable modules. If this was the case in empeg and the part we need changed was indeed a module, we would not need to recompile the whole affair.