Busbox missing fdisk and fsck: How to add?

[Gilles <codecomplete@free.fr>]

Hello,

On an ARM appliance, as a way to run fsck on a USB keydrive that holds 
/boot and /, I was thinking of running a small Linux image from RAM 
after downloading it through TFTP.

Problem is, the Busybox it contains is missing fdisk and fsck:

========
BusyBox v1.22.1 (Debian 1:1.22.0-19+b3) built-in shell (ash)
Enter 'help' for a list of built-in commands.

~ # help
Built-in commands:
------------------
        . : [ bg break cd chdir command continue echo eval exec exit
        export false fg getopts hash help history jobs kill let local
        printf pwd read readonly return set shift test times trap true
        type ulimit umask unset wait

~ # fdisk -l
/bin/sh: fdisk: not found

~ # fsck /dev/sda1
/bin/sh: fsck: not found
========

It does contain wget, however: Is there a way to download a compatible 
fsck binary from somewhere?

Thank you.