update to sepecific version package

On rhel 5.3 I want to update to kernel version "2.6.18-128.8.1.el5"
due to a security patch.

when performing:

# yum check-update | grep kernel
kernel.x86_64                            2.6.18-164.2.1.el5
rhel-x86_64-server-5
kernel-devel.x86_64                      2.6.18-164.2.1.el5
rhel-x86_64-server-5
kernel-headers.x86_64                    2.6.18-164.2.1.el5
rhel-x86_64-server-5

But 2.6.18-164.2.1.el5 correspond to rhel 5.4, and I dont want to move
to this version, I want to keep rhel 5.3.

I tried :

# yum update kernel-2.6.18-128.8.1

But it seems to be the wrong way.

How could I instruct yum to update the server to this specific kernel version?

Thanks in advance