• you need gcc and nasm
• you need dd and mcopy for generated the raw floppy image

• install cross gcc for Cygin (build by myself) http://julu.myweb.hinet.net/Share/cygwin_toolchain4_bos0821.tgz
  (md5sum: e06bdccb2c44c4cc65097399e8722d95)
• use cygwin setup to install nasm
• download from http://www.gnu.org/s/mtools/download.html
  ./configure
  make
  make install
  (ps: /usr/local/bin/mcopy will be used)

• install xcode (tested with 4.0.2)
• install cross gcc for OSX
  http://crossgcc.rts-software.org/doku.php -- gcc-4.5.2-for-linux32.dmg (65.2 MB)
  install to /usr/local/gcc-4.5.2-for-linux32/
  -- gcc-4.5.2-for-linux64.dmg (71.7 MB)
  /usr/local/gcc-4.5.2-for-linux64/
  

• download from http://www.gnu.org/s/mtools/download.html
• build it with following configuration env CFLAGS="-arch i386" LDFLAGS="-arch i386 -liconv" ./configure
  make
  sudo make install
  

sudo brew install qemu nasm

• the most easy way to setup your environment on ubuntu by excuting script

  sh ./scripts/setup_ubuntu.sh

• install nasm
  

$ sudo apt-get install nasm
(NASM version 2.08.01 compiled on Jun 5 2010)
(NASM version 2.09.04 compiled on Nov 26 2010)

• install qemu
  $ sudo apt-get install qemu
  (tested with qemu version : 0.12.5 - 0.14.0)

• install mtools
  $ sudo apt-get install mtools (Used to mcopy the MYOS.BIN to floppy image without root permission)

• install nasm
  $ sudo yum install nasm
  (NASM version 2.07 compiled on Jul 15 2010)

• install qemu
  $ sudo yum install qemu
  (testied boot successfully with qemu version: 0.11.0)

make

• make package
• previous command generated image file
  -- ./bos.img # a floppy image with vfat-12

• make run # run with qemu-system-x86_64