Kernel

mount /boot
eselect kernel list
cd /usr/src/linux
make menuconfig
make && make modules_install
cp arch/x86_64/boot/bzImage /boot/kernel-xxx
cp .config /boot/config-xxx

Initramfs

genkernel --install --no-ramdisk-modules --lvm initramfs

Grub

grub2-mkconfig -o /boot/grub/grub.cfg