The way I would go about installing a different fedora versions kernel is:
su -c 'yum install rpmdevtools yum-utils'
su -c 'yum-builddep kernel-184.108.40.206-6.fc15.src.rpm'
rpmbuild --rebuild --with baseonly --without debuginfo --target=`uname -m` kernel-220.127.116.11-6.fc15.src.rpm
and when finished you should have the new kernel.rpm in your ~/rpmbuild/RPM/...i686 or xx86_64 folder. You can then cd to the folder and install with something like:
cd /home/YOURUSERNAME/rpmbuild/RPMS/XXXXXis either i686 or X86_64/
yum localinstall --nogpgcheck kernel-<version>.rpm
---------- Post added at 03:53 PM ---------- Previous post was at 03:43 PM ----------
EDIT: It is definitely a good idea to edit /boot/grub/grub.conf and match the following lines before a reboot: