Quick Primer: linux kernel module loading
According to some kernel module docs from the CentOS project, it is more than likely that iptables will load the kernel module as needed.
Let’s find out by looking at the loaded kernel modules, restarting iptables (after having built and installed the iptables module), and then looking again at the loaded kernel modules:
lsmod | grep ipt_ #the above returns a list of iptables modules (with the preface of ipt_, which I believe is a convention for iptables modules) service restart iptables lsmod | grep ipt_
You must enable the kernel modules in the iptables config in /etc/sysconfig/iptables-config. The option is called IPTABLES_MODULES and is a space separated list of iptables kernel module names.