1) Run 'make config' or 'make menuconfig' and select the 
   functionality that you wish to enable.

2) make dep

3) Check the Makefile for any Makefile setting you wish 
    to adjust for your system (things like like setting 
    your cross compiler, adjusting optimizations, etc)

4) make

5) Run 'make install' or 'make PREFIX=/target install' to
    install busybox and all the needed links.