This directory contains the root directory structure that will
be loaded once Linux is in memory and the CDROM has been detected.
It is loaded as a RAM disk and replaces the initrd. It is in fact a
quite complete set of commands, and you can quite liberally add to 
it. Do so by adding the files you want to either rootsbin.list (note
/bin and /sbin are in the same directory).

Quite a few files will be added to this directory automatically either
by the makekernel script or by the makebinaries script.  Be a bit
careful about what files you add to /etc as it is somewhat tailored to
be a streamlined boot process. In fact, the normal RedHat files in
rc.d, ... are probably not there -- it is rather simplified and reminiscent
of an old Unix system.