How do I enable a USB SuperDrive in Mac OS X El Capitan on a MacBook Pro?
I discovered this is a fast and simple way to enable a USB SuperDrive on El Capitan:


Click on the "" (Apple) menu, select "Restart...", and then hold "⌘" (Command) and "R" at the same time until the progress bar appears. [This will boot El Capitan in recovery mode, which may take a little longer than usual.]
Once booted into the GUI, click on the "Options" menu, and select "Terminal".
Type csrutil disable, and then press return. [This will temporarily disable System Integrity Protection, which is only possible in recovery mode. This will allow us to modify the restricted *.plist file.]
Type plutil -convert xml1 /Volumes/Macintosh\ HD/Library/Preferences/SystemConfiguration/com.apple.Boot.plist, and then press return.
Type vi /Volumes/Macintosh\ HD/Library/Preferences/SystemConfiguration/com.apple.Boot.plist, and then press return.
Add the mbasd=1 flag to the "Kernel Flags" string, and save the file. It should look like the file below:


&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;
&lt;plist version="1.0"&gt;
&lt;dict&gt;
    &lt;key&gt;Kernel Flags&lt;/key&gt;
    &lt;string&gt;mbasd=1&lt;/string&gt;
&lt;/dict&gt;
&lt;/plist&gt;



Type csrutil enable, and then press return.
Type shutdown -r now, and then press return.


Once the system has restarted, you should now be able to use your USB SuperDrive.