[CentOS] newbie kernel question

Im sorry if this is a newb question, but how do you recompile the
kernel in CentOS 4.3? I need to add reiserfs support (even though the
setup detected it) the kernel it gave me didnt have support for
reiserfs, and my entire fileserver is all reiserfs.  I tried the
gentoo way, which im use to and it bombed.  What do i need to do? does
it install kernel source by default? I couldnt find any good
documentation on the subject, and this is my first RH type install.

thanks

Nick