For newer servers like R620 and R630, I was able to just feed the i DRAC any firmware file from Dell's website (BIOS or i DRAC or otherwise) and it figured out what to do with it.
With the advent of VMware ESXi there are fewer and fewer good ways to update your Dell Power Edge system’s firmware, seeing as you can’t just run the System Update Utility from the console OS anymore.
In the administrator mode, select [Network] - [Internet ISW Settings] - [Update Firmware at Specified Time], then configure the following settings.
Download a firmware from the Internet to this machine and update the firmware manually.
Click next and name the shortcut as, say, Restart Options.
Alternatively, you can download and use a simple utility called Boot Safe.
The Minimal option will get selected automatically. Click on the Restart button, and the computer will initiate the process to reboot your computer directly in safe mode.