Hi Joe,
It looks like you are missing OpenMPI.
Are you using the very latest version of sl6.cfg? That's the one here: https://svn.cct.lsu.edu/repos/numrel/simfactory2/trunk/mdb/optionlists/sl6.c.... At the top of that it gives commands for installing gsl-devel and openmpi-devel. The second of these should provide the necessary OpenMPI.
hwloc selected, but HWLOC_DIR not set. Checking some places...
I was able to get past that by installing hwloc-devel using yum as well.
Unfortunately, the version provided by hwloc-devel is too old. If you use the latest sl6.cfg it will build hwloc instead.
Barry