After a hard drive failure and replacement, I reinstalled OS X with “printer drivers” un-checked.  Of course it would be easy to get the ONE driver I needed later, right?  Wrong.  It wasn’t super-difficult, but I figured I’d save y’all the trouble of repeating the research…

How to Install the Brother MFC7820N Driver
For OS X users at IndyHall
The Abridged Instructions:

1. Download this Brother Printer Driver:  Brother MFC-7820N.gz, and double-click to un-gzip it.
2. Open System Preferences > Print & Fax.
3. Add a printer (+), select Print Using: “Other…”, choose the file “Brother MFC-7820N”
4. Click “OK”, print a test page… you’re done!

Director’s Cut:

Here’s what I had to do to gain access to the IndyHall printer… documenting this as I do it, and will summarize afterward.

1. Google search: “os x install printer drivers from dvd”
   Result 1 looked promising:  Installing printer drivers only – OS X Server – MacTalk Forums
2. Reply to forum question mentions “Pacifist” as software that will let you get the printer drivers off the install dics… but there’s no link.
3. Google search: “os x pacifist”
   Result 1 wins again: CharlesSoft – software you always wished someone would write
4. Downloaded and installed Pacifist, which lets you look inside the OS X install discs or installer packages.
5. Ran the app, clicked on the “Open Apple Install Discs” button (duh)
6. Searched down through the directories and found my Brother driver at:
   • Contents of OSInstall.mpkg
     • Contents of PrinterDriversGroup
       • Contents of BrotherPrinterDrivers.pkg
         • Library
           • Printers
             • PPDs
               • Contents
                 • Resources
                   • Brother MFC-7820N.gz
7. Dragged-and-dropped that file to the desktop (had to enter admin password), then double-clicked the file to un-gzip it
8. Opened OS X System Preferences > Print & Fax
9. Clicked on “+” below left table to add a printer
10. Selected the printer from the list of available printers
11. In the “Print Using” drop-down menu, selected “Other…”, which opened a find-file sheet.
12. Picked the brother driver from the desktop… but hesitated, wondering if I should store the printer driver elsewhere before doing this.  Asked Allum, who said to just go for it.  Clicked “OK”.
13. Printed a test page with no problems… printer installed!