This is the easiest (and most efficient) method i've found - anything easier please let me know.
Get the Bios upgrade DOS executable from Dell or your vendor and rename it to something like bios.exe
1. Go to http://www.hiren.info/pages/bootablecd and download the zipped files. You can forget those instructions, but the files are very well done and planned out. Extract.
2. Go to http://www.winimage.com/download.htm and download the zip. Not a bad idea to buy it if you will use it more than once, since it seems to last 30 days in trial mode.
3. Execute winimage, and open the file bootCD\CD\Floppy.ima that you extracted before.
4. From the menu, Image, Inject, and choose your bios.exe. If the file is too big, first make the "floppy" 2.88 mb in size with Image, Change Format. Save, close.
5. That's it! Use the edited bootCD\CD\Floppy.ima with your drac or ilo as a virtual floppy image.
Whatever you choose when you load (I do the shift+f5), you can see the file is there with a "dir"; just type "bios" and you will be flashing.
It's amazing how difficult these 5 steps are to find with a google search.
What if you need ISO? In the bootCD folder, there's a Build-ISO.cmd script that will create an ISO using that Floppy.ima that you already injected with your bios update executable. So, that would go after step 4 above.