I don't really know anything about this, but you say you have a patch? You can use the patch command to patch the *.c file assuming that is what the patch is for. Then you should be able to re-compile the kernel. I'm pretty sure that's how it would be done. Do you have any more specific information about what you are trying to accomplish? I don't know anything about memory duplication but someone else might be able to help if you give some more info.
Use 'man patch' for more information.