Hello Jeff and Kiril, Thank you for your responses. Based on the information you both provided, I was able to get buildrpm to make the OMPI RPM the way I wanted. I ended up having to define _prefix , _mandir , and _infodir .
Additionally, I found I had to use --define "shell_scripts_basename mpivars" because without that, when I tried to use mpi-selector, mpi-selector did not find the installation since it specifically seems to look for the shell scripts as mpivars.{sh,csh} rather than mpivars-1.3.3.{sh,csh} as the .spec file builds. I think the .spec file should be changed to match what mpi-selector expects. Jeff, it might also be really useful to have a .spec build option to allow the RPM to register itself as the system default. I hand-modified the .spec file to do this. Please let me know if I should register a feature request somewhere more formally. Thanks again to you both, and sorry for taking so long to reply.