Se voce tiver os discos de instalacao pode copiar eles em uma pasta por exemplo /stage/
E deve adicionar essas informacoes criando um arquivo  media.repo na pasta /etc/yum.repos.d assim o yum ira funcionar normalmente.

/etc/yum.repos.d
[root@srvoracle01 yum.repos.d]# pwd
/etc/yum.repos.d
[root@srvoracle01 yum.repos.d]# cat media.repo
[media]
name=Red Hat Enterprise Linux $releasever
baseurl=file:///stage/redhat/Server/
enabled=1
gpgcheck=0

Ou seguir os passos abaixo para fazer a configuracao do repositorio do YUM.

Getting Started

   1. Download and Install Enterprise Linux
   2.

      Download and copy the appropriate yum configuration file in place, by running the

following commands as root:
      Oracle Enterprise Linux 4, Update 6 or Newer

      # cd /etc/yum.repos.d
      # mv Oracle-Base.repo Oracle-Base.repo.disabled
      # wget http://public-yum.oracle.com/public-yum-el4.repo

      Oracle Enterprise Linux 5

      # cd /etc/yum.repos.d
      # wget http://public-yum.oracle.com/public-yum-el5.repo

      Oracle VM 2

      # cd /etc/yum.repos.d
      # wget http://public-yum.oracle.com/public-yum-ovm2.repo

   3.

      Enable the appropriate repository by editing the yum configuration file
          * Open the yum configuration file in a text editor
          * Locate the section in the file for the repository you plan to update from,

e.g. [el4_u6_base]
          * Change enabled=0 to enabled=1
   4.

      Begin using yum, for example:

      yum list

      yum install firefox

You may be prompted to confirm the import of the Oracle OSS Group GPG key.

(http://public-yum.oracle.com/)