Как установить бинарный RPM пакет в тестовую директорию?

Не совсем то, но всеже ...

man rpm
   GENERAL OPTIONS
       These options can be used in all the different modes.

       --root DIRECTORY
              Use the file system tree rooted at  DIRECTORY  for  all  opera-
              tions.  Note that this means the database within DIRECTORY will
              be used for dependency checks and any scriptlet(s) (e.g.  %post
              if  installing,  or  %prep  if building, a package) will be run
              after a chroot(2) to DIRECTORY.

И еще:
   INSTALL AND UPGRADE OPTIONS
       The general form of an rpm install command is

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