After
emerge -av git
dispatch-conf that some git daemon need it, I gave

cd /usr/src
git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-stable
mount /dev/sda6 /boot

unfortunately 
eselect kernel list didn't show up linux-stable so I gave

unlink linux
ln -s linux-stable linux 
cd linux

and

git bisect start | tee -a /root/bisect.log
git bisect bad v3.6.11 | tee -a /root/bisect.log
git bisect good v3.5.7 | tee -a /root/bisect.log

And for only the first time I used
zcat /proc/config.gz > /usr/src/linux/.config
make oldconfig

I can recall that oldconfig gave me no options at all. But since it was the first time I decided to continue with
make -j2 && make modules_install
cp arch/x86_64/boot/bzImage /boot/gentoo-bisect

and modified accordingly my boot with
cd /boot/grub
nano menu.lst

after reboot the procedure went as

cd /usr/src/linux
mount /dev/sda6 /boot
git bisect good | tee -a /root/bisect.log
cp ../linux-3.5.7-gentoo/.config
cp ../linux-3.5.7-gentoo/.config .config
make oldconfig
make -j2 && make modules_install

I think without need, I gave here and only here as I dont use initramfs
make install
cp arch/x86_64/boot/bzImage /boot/gentoo-bisect

and rebooted
after that the procedure repeated like

cd /usr/src/linux
 mount /dev/sda6 /boot
 git bisect good | tee -a /root/bisect.log
 OR  git bisect bad | tee -a /root/bisect.log
 cp ../linux-3.5.7-gentoo/.config .config
 make oldconfig
 make -j2 && make modules_install
 cp arch/x86_64/boot/bzImage /boot/gentoo-bisect
 reboot