[CentOS] rebuilding the kernel.

Hello folks,

I am trying to add HDLC module support in the menuconfig. However, I am 
facing difficulties in rebuilding the kernel and modules. My main 
objective is to get the HDLC supported in kernel 2.6.9. I have a CentOS 
4.4 with kernel 2.6.9.42. I need help in finding the best way to add the 
HDLC support whether through getting an RPM package for it or refering 
me to the right procedure in rebuilding the kernel.

Thank you very much in advance for your help.