In addition to the files pertaining to the RPP system that reside in /var/adm/rpp, there are two other special locations that are reserved for RHC Linux configuration and operation.
The control-panel and related tools put lots of stuff in /usr/lib/rhs. There is probably nothing here that you would want to edit, it is mostly small scripts, bitmaps and text files.
The other location, /etc/sysconfig, is used to store configuration information. The major users of the files in this directory are the scripts that run at boot time. It is possible to edit these by hand, but it would be better to use the proper control-panel tool.