The easiest way:

  1. Download correct iso DELL SLI version depends on PowerEdge generation.
  2. Burn it 🙂
  3. Download needed files for example on USB drive.
  4. Boot Dell from CD drive.
  5. Mount USB drive (should be done automaticaly).
  6. Run terminal and switch to root account.
  7. Execute files from USB drive.
  8. Reboot.