I followed the instructions at 
DROID Bionic Receiving Mysterious 5.9.901 Update? – Droid Life I got the file from the mirror site there. No rooting required.
To add to the instructions:
1.  Download the file from above and drop it on the root of your SD card (not internal storage). That is SD-EXT
2.  Power phone down
3.  Reboot into stock recovery (adb reboot recovery) by holding Power and Volume Up/Down at the same time.
4.  When the robot appears, press both volume keys in at the same time.
5.  Select “apply update from sdcard” using the volume keys, then the power switch to initiate it.
6.  Choose the file that you downloaded above, press Power and let it load.
7.  When the install is done, press the Power button, It'll reboot, but it'll be longer than normal (a few minutes)