How to install packages to a custom location in centos6

the installroot tool is usefull for situations like installing packages into a chroot environment. try installing all the yum configuration and repo files into /tp, keeping their respective paths, and your custom package installation will work. (eg: /tp/etc/yum.conf).

in such a case /tp will be prepended to any files that are read or written by yum. that includes configurations files, yum log files, repository information, etc.

From the rpm man page:

   --prefix NEWPATH
          For relocatable binary packages, translate all file  paths  that
          start  with  the  installation  prefix in the package relocation
          hint(s) to NEWPATH.

   --relocate OLDPATH=NEWPATH
          For relocatable binary packages, translate all file  paths  that
          start with OLDPATH in the package relocation hint(s) to NEWPATH.
          This option can be used repeatedly if several OLDPATH's  in  the
          package are to be relocated.