From nookDevs

Part of the NookColor portal

BusyBox is a single multicall binary that packages the functionality of most widely used standard Unix tools. Follow the simple steps below to install BusyBox on rooted Android device.

BusyBox combines tiny versions of many common UNIX utilities into a single small executable. It provides replacements for most of the utilities you usually find in GNU fileutils, shellutils, etc. BusyBox provides a fairly complete environment for any small or embedded system.

How to Install BusyBox on rooted NookColor

Note: You must have already installed su for this to work.

1. Download BusyBox for arm61 from here: Binary from busybox.net.
2. Reboot your android device normally and plug in to your PC.
3. Open the command prompt/console and cd to the SDK/tools dir. At the prompt:
   1. adb shell
   2. su
   3. mount -o remount,rw /dev/block/mmcblk0p5 /system
   4. exit
   5. exit

      (we have to exit twice because we were in su.)

4. Now, you're out of the adb shell, back to your command prompt, we're going to adb to push our busybox binary onto the nook.
   1. adb push busybox /data/local
5. And now, back to the shell to finish the install.
   1. adb shell
   2. su
   3. mount -o remount,rw /dev/block/mmcblk0p5 /system
   4. cd /system
   5. mkdir /system/xbin

      Now, we use busybox to copy itself into /system/xbin because the adb shell lacks a cp command.

   6. cd /data/local
   7. chmod 755 busybox
   8. /data/local/busybox cp /data/local/busybox /system/xbin/busybox

      Now, we use busybox to install itself, and make the symlinks to the systems commands.

   9. cd /system/xbin
   10. chmod 755 busybox
   11. ./busybox --install -s /system/xbin

       Now, we don't need to copy we pushed into /data/local any more...

   12. rm /data/local/busybox

       Then exit and reboot:

   13. reboot