In order tho apply the patches you only need to cd /path/of/kernel_sources
(cd /usr/src/linux for example) and then patch -p1 < /path/of/your/patch .
The howto on gentoo-wiki is still a work in progress. I keep adding informations or notes. Several problems and possible solutions have come up, along with suggestions and questions. If you have any of these feel free to comment here: http://gentoo-wiki.com/Talk:HOWTO_Mi..._Keyboard_4000